Wholesale VoIP Routes: The Complete Guide to High-Quality Voice Routing, Pricing, Optimization & Carrier Selection (2026)
Introduction
Global voice communications have evolved far beyond traditional telephone networks. Today, businesses, telecom carriers, Internet Telephony Service Providers (ITSPs), call centers, CPaaS platforms, and wholesale operators rely on Wholesale VoIP Routes to deliver millions of international calls every day with high quality, low latency, and competitive pricing.
However, purchasing wholesale routes isn’t simply about finding the lowest price. A route that appears inexpensive on paper can quickly become costly if it suffers from poor call quality, high post-dial delay (PDD), low answer-seizure ratio (ASR), or frequent routing failures. In wholesale voice, profitability depends on balancing cost, quality, reliability, and intelligent routing strategies.
As global voice traffic continues to increase and customer expectations rise, network operators must evaluate route quality using measurable performance metrics rather than price alone. They also need to understand how wholesale routing works behind the scenes, how carriers optimize traffic in real time, and how modern technologies such as AI-powered routing, dynamic least-cost routing (LCR), and automated failover are reshaping the industry.
Whether you’re launching a new VoIP business, expanding your carrier network, or optimizing an existing voice infrastructure, understanding wholesale routes is essential for delivering reliable international calling services while maximizing operational efficiency and profit margins.
This comprehensive guide explains everything you need to know, including:
- What Wholesale VoIP Routes are and how they work?
- The different types of wholesale voice routes.
- How wholesale call termination is performed step by step?
- The differences between CLI, Non-CLI, and CC routes.
- Quality metrics every buyer should monitor.
- How pricing, rate decks, and billing increments affect profitability?
- Best practices for selecting high-quality carriers.
- Common mistakes to avoid.
- Future trends shaping wholesale voice routing in 2026 and beyond.
By the end of this guide, you’ll have a practical framework for evaluating providers, optimizing voice quality, reducing costs, and building a resilient wholesale VoIP infrastructure.
What Are Wholesale VoIP Routes?
Wholesale VoIP Routes are international voice paths that enable telecommunications providers to deliver calls between different networks using Internet Protocol (IP) instead of the traditional Public Switched Telephone Network (PSTN).
Rather than connecting directly to every destination worldwide, service providers purchase access to wholesale routes from specialized carriers that already maintain extensive interconnections with mobile operators, fixed-line providers, and global telecom networks.
Think of a wholesale route as a carefully engineered pathway that carries a voice call from its origin to its destination through multiple interconnected networks. The quality, reliability, and cost of that pathway determine the overall calling experience.
Unlike retail VoIP services designed for individual businesses or consumers, wholesale routes operate at carrier scale, handling thousands—or even millions—of concurrent international calls every day.
Why Wholesale VoIP Routes Matter
For telecom operators, every outbound call represents both a service opportunity and a financial decision.
Selecting the wrong route can lead to:
- Poor voice quality
- High latency
- Frequent call failures
- Increased customer complaints
- Lost revenue
- Carrier penalties
- Reduced customer retention
Conversely, selecting high-quality routes helps providers:
- Improve customer satisfaction
- Increase answer rates
- Reduce operational costs
- Optimize network utilization
- Expand global coverage
- Maximize profit margins
- Maintain service-level agreements (SLAs)
In competitive markets such as the United States and Europe, route quality has become a key differentiator. Businesses increasingly prioritize consistent call performance over marginal cost savings, making intelligent route management a strategic advantage.
Who Uses Wholesale VoIP Routes?
Wholesale VoIP routing supports a wide range of organizations across the telecommunications ecosystem.
Internet Telephony Service Providers (ITSPs)
ITSPs use wholesale routes to terminate international calls without building direct interconnections in every country. This allows them to offer competitive global calling services while maintaining flexible operating costs.
Telecom Carriers
National and international carriers purchase wholesale routes to extend network coverage, improve redundancy, and optimize traffic distribution across multiple partners.
Call Centers
Outbound and inbound contact centers rely on high-quality routes to ensure reliable customer interactions, especially for sales, customer support, collections, and appointment reminders where call clarity directly impacts business outcomes.
CPaaS Providers
Communications Platform as a Service providers integrate wholesale voice routes into APIs that enable developers to build voice-enabled applications, automated notifications, authentication calls, and omnichannel communication platforms.
Wholesale Voice Providers
Wholesale carriers buy and sell voice traffic between international operators, constantly optimizing routing decisions based on quality metrics, pricing, and network performance.
Enterprise Businesses
Large multinational enterprises with global offices often use wholesale-grade voice infrastructure through managed providers to reduce communication costs while maintaining enterprise-grade reliability.
How Wholesale VoIP Call Termination Works, Step by Step
One of the biggest misconceptions about wholesale voice services is that a phone call travels directly from the caller to the recipient. In reality, every international VoIP call passes through multiple intelligent network components before reaching its destination.
Understanding this journey helps explain why route quality, carrier selection, and routing policies have such a significant impact on both call quality and operating costs.
The Wholesale Call Flow
Caller
│
IP Phone / PBX
│
Session Border Controller (SBC)
│
Softswitch
│
Routing Engine (LCR / Quality Routing)
│
Wholesale Carrier
│
Tier-1 or Direct Carrier
│
Destination Network
│
Recipient
Each component in this chain plays a specific role in ensuring that the call reaches its destination efficiently, securely, and with the highest possible voice quality.
Step 1: The Call Originates
The process begins when a user places a call from an IP phone, softphone, SIP trunk, PBX system, or cloud communications platform.
At this stage, the voice signal is converted into IP packets using audio codecs such as G.711, G.729, or Opus, depending on network conditions and service requirements.
Step 2: Session Border Controller (SBC)
The call is then processed by a Session Border Controller.
The SBC acts as the first line of defense for the network by:
- Authenticating SIP sessions
- Preventing unauthorized access
- Protecting against SIP attacks
- Managing NAT traversal
- Encrypting voice traffic when required
- Maintaining interoperability between different networks
Without an SBC, wholesale voice networks would be significantly more vulnerable to fraud, denial-of-service attacks, and interoperability issues.
Step 3: Softswitch Processing
Once authenticated, the call reaches the softswitch—the operational brain of a wholesale voice network.
The softswitch is responsible for:
- User authentication
- Call authorization
- Codec negotiation
- Billing integration
- Call logging
- Route selection
- Policy enforcement
- Carrier management
Modern cloud softswitches can process hundreds of thousands of simultaneous call sessions while continuously evaluating route performance in real time.
Step 4: Intelligent Route Selection
Instead of selecting a fixed path, the routing engine evaluates multiple available carriers based on predefined policies.
These policies may include:
- Least Cost Routing (LCR)
- Quality-Based Routing
- Priority Routing
- Geographic Routing
- Time-Based Routing
- Load Balancing
- Dynamic Carrier Ranking
- Automatic Failover
For example, if Carrier A offers the lowest rate but its ASR has dropped below an acceptable threshold, the routing engine may automatically choose Carrier B to preserve call quality.
This dynamic decision-making process is one of the key reasons modern wholesale VoIP networks outperform traditional static routing models.
Step 5: Wholesale Carrier Processing
After route selection, the chosen wholesale carrier accepts the call and forwards it through its own network infrastructure.
Large wholesale providers maintain direct interconnections with hundreds of operators worldwide, allowing them to deliver calls efficiently across multiple regions while minimizing latency.
Step 6: Destination Carrier
The destination carrier receives the call and routes it into the local telephone network, whether mobile, fixed-line, or enterprise.
Depending on the destination, this may involve:
- Mobile Network Operators (MNOs)
- Fixed-Line Operators
- National Carriers
- Regional Telecom Providers
- Enterprise SIP Networks
Step 7: Call Completion
Finally, the recipient’s device rings, and the call is established.
Throughout the entire conversation, network components continuously monitor packet delivery, latency, jitter, and call stability to ensure a consistent voice experience.
Why Understanding the Call Flow Matters
Every stage in the wholesale routing process influences call quality, operating costs, and customer satisfaction.
A weak SBC configuration may expose the network to fraud.
A poorly configured routing engine may select low-quality carriers.
An unreliable upstream provider may increase latency or reduce answer rates.
Understanding these dependencies enables telecom operators to troubleshoot issues faster, optimize routing policies, and make informed decisions when evaluating wholesale providers.
Types of Wholesale VoIP Routes
Not all wholesale VoIP routes are created equal. While many providers advertise “premium quality” or “low-cost international termination,” the reality is that each route type is designed for different business objectives.
Some prioritize crystal-clear voice quality, while others focus on reducing costs for high-volume traffic. Choosing the wrong route can lead to poor customer experiences, reduced Answer-Seizure Ratios (ASR), increased support tickets, and lower profit margins.
Understanding the characteristics of each route type allows operators to align routing decisions with their business goals rather than relying solely on price.
Premium Routes
Premium Routes are considered the highest-quality wholesale VoIP routes available. They are typically delivered through direct carrier interconnections or trusted Tier-1 providers, ensuring minimal packet loss, low latency, and excellent call completion rates.
These routes are ideal for businesses where voice quality directly impacts customer satisfaction or revenue.
Key Characteristics
- Direct or near-direct carrier connections
- High ASR and ACD
- Excellent voice clarity
- Low PDD (Post-Dial Delay)
- Minimal jitter and packet loss
- Stable long-term performance
- Strong SLA commitments
Best For
- Financial institutions
- Healthcare providers
- Government communications
- Enterprise businesses
- Executive communications
- Customer support centers
- High-value international clients
Advantages
- Outstanding voice quality
- Reliable call completion
- Lower customer complaints
- Better customer retention
- Consistent network performance
Considerations
Premium routes generally come at a higher cost than standard alternatives, but they often generate a stronger return on investment by reducing failed calls and improving customer experience.
Standard Routes
Standard Routes offer a balanced combination of quality and affordability.
Rather than using exclusively direct interconnections, these routes may pass through several trusted wholesale carriers while still maintaining acceptable performance levels.
They are among the most commonly used route types in the wholesale voice industry.
Best For
- SMB VoIP providers
- International business communications
- General enterprise traffic
- Moderate-volume voice services
Advantages
- Competitive pricing
- Good voice quality
- Wide international coverage
- Flexible scalability
Limitations
Quality may vary depending on the destination country and upstream carrier relationships.
Value Routes
Value Routes prioritize cost savings over premium call quality.
They are designed for operators managing large traffic volumes where keeping costs low is more important than achieving the highest possible voice performance.
Although these routes may experience occasional quality fluctuations, they remain suitable for many commercial applications.
Common Use Cases
- High-volume outbound campaigns
- Promotional calls
- Non-critical voice traffic
- Emerging markets
- Price-sensitive customers
Direct Routes
Direct Routes terminate calls directly into the destination operator’s network without relying on multiple intermediary carriers.
Because there are fewer network hops, these routes generally provide superior reliability and lower latency.
Benefits
- Faster call setup
- Better audio quality
- Lower latency
- Higher call completion rates
- Reduced routing complexity
Direct routes are especially valuable for destinations where voice quality is a top priority or where regulatory compliance requires direct carrier relationships.
Tier-1 Routes
Tier-1 Routes are provided by carriers that own extensive global telecommunications infrastructure and maintain direct peering agreements with numerous international operators.
These carriers typically operate large backbone networks capable of handling millions of voice sessions simultaneously.
Characteristics
- Extensive international reach
- High network redundancy
- Carrier-grade infrastructure
- Excellent uptime
- Strong service-level agreements
Best For
- International telecom operators
- Wholesale carriers
- Large cloud communication providers
- Global enterprises
Tier-2 Routes
Tier-2 carriers purchase capacity from Tier-1 providers and redistribute voice traffic to regional markets.
Although they generally offer lower pricing, performance may vary depending on the quality of their upstream providers.
Advantages
- Competitive rates
- Flexible commercial agreements
- Strong regional expertise
Considerations
Careful quality monitoring is essential when working with Tier-2 providers.
Static Routes
Static Routes follow predefined routing paths that remain unchanged until manually updated.
Advantages
- Predictable routing behavior
- Easier troubleshooting
- Consistent traffic management
Disadvantages
- Limited flexibility
- Slower response to network failures
- Manual optimization required
Static routing is commonly used in highly controlled enterprise environments.
Dynamic Routes
Dynamic Routes automatically adapt to changing network conditions.
Routing engines continuously evaluate carrier performance and select the most appropriate route based on predefined quality and pricing rules.
Modern cloud softswitches increasingly rely on dynamic routing to optimize network performance in real time.
Benefits
- Automatic route optimization
- Higher availability
- Better call quality
- Reduced operational workload
- Intelligent traffic distribution
Hybrid Routes
Hybrid routing combines multiple routing strategies into a single intelligent framework.
For example:
- Premium routes for VIP customers
- Standard routes for business traffic
- Value routes for marketing campaigns
This approach allows operators to maximize profitability while maintaining service quality where it matters most.
CLI, Non-CLI, and CC Routes: Choosing the Right Wholesale VoIP Route Type
One of the most important decisions wholesale voice buyers make is selecting the appropriate caller identification method.
Although pricing often attracts the most attention, the type of route you choose significantly affects answer rates, customer trust, regulatory compliance, and overall call success.
What Are CLI Routes?
CLI (Calling Line Identification) Routes transmit the caller’s authentic phone number to the recipient.
When the recipient answers the phone, they see the correct originating number rather than an anonymous or substituted caller ID.
Benefits
- Higher answer rates
- Greater customer trust
- Improved brand reputation
- Better regulatory compliance
- Reduced spam detection
- Essential for enterprise communications
Recommended For
- Customer support
- Financial services
- Healthcare organizations
- Authentication calls
- Business communications
- Government agencies
What Are Non-CLI Routes?
Non-CLI Routes either suppress or replace the caller ID before the call reaches the destination.
Because the recipient cannot verify the origin of the call, these routes typically experience lower answer rates.
Advantages
- Lower pricing
- Suitable for certain bulk traffic scenarios
- Available in destinations where CLI support is limited
Risks
- Reduced customer confidence
- Higher likelihood of call rejection
- Potential regulatory restrictions
- Increased spam filtering
What Are CC Routes?
CC (Call Center) Routes are specifically optimized for high-volume outbound and inbound call center operations.
Unlike standard wholesale routes, CC routes are engineered to handle sustained traffic volumes while maintaining stable call quality and predictable performance.
Common Features
- Optimized for continuous outbound dialing
- Improved route stability
- Better congestion management
- High concurrent call capacity
- Enhanced routing consistency
Best For
- Contact centers
- Customer service departments
- Telemarketing operations
- Debt collection agencies
- Appointment reminder systems
Comparing CLI, Non-CLI, and CC Routes
| Feature | CLI Routes | Non-CLI Routes | CC Routes |
|---|---|---|---|
| Caller ID Visibility | ✅ Yes | ❌ No | ✅ Usually |
| Voice Quality | Excellent | Variable | High |
| Customer Trust | Very High | Low | High |
| Average Cost | Higher | Lower | Moderate |
| Answer Rates | High | Lower | High |
| Compliance | Strong | Depends on destination | Strong |
| Best Use Case | Enterprise communications | Cost-sensitive traffic | High-volume call centers |
Expert Recommendation
If your business depends on customer engagement, brand reputation, or regulatory compliance, CLI routes should be your default choice.
Non-CLI routes should only be used after carefully evaluating destination regulations and understanding the potential impact on call completion rates.
For organizations operating large contact centers, dedicated CC routes provide the best balance between scalability, reliability, and operational efficiency.
Choosing the Right Route for Your Business
Different business models require different routing strategies. There is no universal solution that fits every organization.
| Business Type | Recommended Route |
|---|---|
| Enterprise PBX | Premium CLI |
| International Carrier | Tier-1 + Dynamic Routing |
| Wholesale Provider | Hybrid Routes |
| Outbound Call Center | CC Routes |
| Authentication Platform (OTP) | Direct CLI Routes |
| CPaaS Provider | Premium + Dynamic LCR |
| Budget VoIP Provider | Standard Routes |
| Marketing Campaigns | Value Routes (where compliant) |
Expert Tip: Instead of relying on a single route type, build a diversified routing strategy that combines Premium, Standard, and Dynamic Routes. This improves resilience, reduces dependency on a single carrier, and enables intelligent failover during outages or congestion.
How Wholesale Routes Are Selected
Many businesses assume that once a call enters a carrier’s network, it automatically follows the shortest or cheapest path. In reality, modern wholesale voice networks use sophisticated routing engines that evaluate multiple factors before selecting the optimal route for every individual call.
A single destination may have dozens—or even hundreds—of available routes offered by different carriers. The routing engine continuously analyzes pricing, quality metrics, network availability, historical performance, and routing policies before making a decision in milliseconds.
This intelligent routing process is what separates carrier-grade wholesale providers from low-cost resellers.
Least Cost Routing (LCR)
Least Cost Routing (LCR) is the most widely used routing strategy in the wholesale VoIP industry.
Its primary objective is simple: deliver calls through the lowest-cost route that still meets predefined quality requirements.
Instead of sending every call through the same carrier, the routing engine compares available rates from multiple providers and dynamically selects the most economical option.
How LCR Works
- A call request reaches the softswitch.
- The routing engine identifies all carriers capable of terminating the destination.
- It compares buy rates from each provider.
- Quality thresholds are checked.
- The lowest-priced qualifying route is selected.
- If the preferred carrier is unavailable, the system automatically moves to the next available route.
Advantages
- Reduces operating costs
- Improves profit margins
- Supports automatic carrier selection
- Simplifies international routing
Potential Drawbacks
Using price as the only decision factor can negatively affect:
- Voice quality
- Call completion rates
- Customer satisfaction
- Long-term profitability
For this reason, modern wholesale operators rarely rely on pure LCR alone.
Quality-Based Routing
Quality-Based Routing prioritizes call performance instead of price.
The routing engine continuously measures each carrier’s performance using live network statistics and historical data.
Rather than choosing the cheapest provider, it selects the route most likely to deliver a successful, high-quality call.
Typical Evaluation Factors
- ASR (Answer-Seizure Ratio)
- ACD (Average Call Duration)
- PDD (Post-Dial Delay)
- Packet loss
- MOS score
- Latency
- Jitter
- Historical route stability
This approach is commonly used for:
- Enterprise communications
- Financial services
- Emergency services
- Premium international traffic
- Executive communications
Priority Routing
Priority Routing follows a predefined hierarchy established by network administrators.
For example:
Priority 1 → Direct Carrier
Priority 2 → Tier-1 Carrier
Priority 3 → Regional Carrier
Priority 4 → Backup Provider
The system always attempts to use the highest-priority route first. If that carrier becomes unavailable or fails to meet quality thresholds, traffic automatically shifts to the next available option.
This strategy is particularly effective when operators have trusted long-term carrier partnerships.
Load Balancing
Large wholesale providers rarely send all traffic through a single carrier.
Instead, they distribute traffic across multiple providers simultaneously to improve efficiency and reduce congestion.
Benefits
- Better resource utilization
- Reduced network overload
- Improved redundancy
- Higher availability
- Greater resilience during traffic spikes
Load balancing also prevents excessive dependence on a single upstream provider.
Geographic Routing
Geographic Routing selects carriers based on the destination region rather than applying identical routing rules worldwide.
For example:
- One carrier may consistently deliver excellent quality in Germany.
- Another may perform better in Brazil.
- A third may offer superior connectivity in Southeast Asia.
Rather than forcing one provider to handle every destination, geographic routing assigns traffic to the strongest regional performer.
This strategy improves:
- Call quality
- Route efficiency
- Customer satisfaction
- Cost optimization
Time-Based Routing
Network performance changes throughout the day.
During peak hours, some carriers experience congestion, while others maintain stable performance.
Time-Based Routing automatically adjusts carrier preferences according to predefined schedules or historical traffic patterns.
For example:
- Premium carriers during business hours
- Cost-optimized carriers overnight
- Specialized routing for weekends
- Seasonal routing adjustments
This approach maximizes both service quality and profitability.
Automatic Failover Routing
Carrier outages are inevitable.
Whether caused by fiber cuts, power failures, signaling issues, or network congestion, interruptions can happen without warning.
Automatic Failover ensures that calls continue flowing without manual intervention.
How It Works
If Carrier A fails:
↓
The routing engine immediately detects the issue.
↓
Carrier B becomes active.
↓
If necessary, traffic shifts again to Carrier C.
↓
Users experience minimal disruption.
This capability is essential for maintaining high service availability and meeting enterprise SLA commitments.
AI-Powered Routing
Artificial Intelligence is rapidly transforming wholesale voice routing.
Instead of relying solely on static rules, AI systems continuously analyze millions of historical call records to predict which carrier is most likely to provide the best outcome for each call.
Modern AI routing engines can evaluate:
- Destination performance trends
- Carrier reliability
- Network congestion
- Time-of-day behavior
- Seasonal traffic patterns
- Historical ASR fluctuations
- Customer-specific routing preferences
Benefits of AI Routing
- Improved call quality
- Faster route optimization
- Reduced manual intervention
- Predictive carrier selection
- Better profit margins
- Continuous self-optimization
As AI adoption grows, predictive routing is becoming a competitive advantage for wholesale operators serving enterprise and carrier customers.
Static vs. Dynamic Route Selection
| Feature | Static Routing | Dynamic Routing |
|---|---|---|
| Manual Configuration | Yes | No |
| Real-Time Optimization | No | Yes |
| Automatic Failover | Limited | Yes |
| Quality Monitoring | Minimal | Continuous |
| Scalability | Moderate | Excellent |
| Best For | Small deployments | Carrier-grade networks |
For most modern wholesale environments, dynamic routing provides greater flexibility, resilience, and long-term operational efficiency.
Building a Multi-Carrier Routing Strategy
Relying on a single wholesale provider creates unnecessary operational risk.
A more resilient approach is to build a multi-carrier ecosystem with intelligent routing policies.
A typical strategy might include:
- Primary Carrier: Premium direct routes for mission-critical traffic.
- Secondary Carrier: Competitive standard routes for routine business communications.
- Backup Carrier: Reliable failover provider for unexpected outages.
- Regional Specialists: Carriers with exceptional performance in specific countries or regions.
This layered architecture improves redundancy, maintains service continuity, and enables continuous optimization based on both quality and cost.
Quality Metrics Every Wholesale VoIP Routes Buyer Should Track
Price alone does not determine the value of a wholesale VoIP route. A low-cost route that produces failed calls, poor audio quality, or customer complaints can quickly become more expensive than a premium alternative.
Professional carriers monitor a set of key performance indicators (KPIs) to evaluate route quality objectively. Understanding these metrics allows buyers to compare providers, detect performance issues early, and optimize routing decisions.
Answer-Seizure Ratio (ASR)
ASR measures the percentage of call attempts that are successfully answered.
Formula:
ASR = (Answered Calls ÷ Total Call Attempts) × 100
Why It Matters
A consistently high ASR indicates that calls are reaching their destinations successfully, while a low ASR may signal routing problems, network congestion, invalid numbers, or poor carrier performance.
General Benchmark:
- Above 60% – Excellent
- 45–60% – Good
- Below 45% – Requires investigation
It’s important to interpret ASR in context, as expected values vary by destination, traffic type, and calling patterns.
Average Call Duration (ACD)
ACD measures the average length of successfully connected calls.
Longer call durations often indicate that users are having meaningful conversations rather than hanging up due to poor quality or connection issues.
Typical Guidelines
- Over 3 minutes – Strong engagement
- 2–3 minutes – Acceptable
- Under 2 minutes – May indicate quality concerns or call setup issues
ACD should always be analyzed alongside ASR for a complete picture of route performance.
Post-Dial Delay (PDD)
PDD is the time between dialing a number and hearing the ringing tone.
Customers expect calls to connect quickly, and excessive delays can create the impression that the network is unreliable.
Recommended Targets
- Under 2 seconds – Excellent
- 2–4 seconds – Acceptable
- Over 4 seconds – Poor user experience
High PDD often points to inefficient routing, overloaded signaling infrastructure, or excessive carrier hops.
Mean Opinion Score (MOS)
MOS is an industry-standard measure of perceived voice quality, typically rated on a scale from 1 (poor) to 5 (excellent).
It reflects the user’s listening experience by considering factors such as clarity, distortion, delay, and packet loss.
MOS Ratings
| MOS Score | Quality |
|---|---|
| 4.3–5.0 | Excellent |
| 4.0–4.3 | Very Good |
| 3.6–4.0 | Acceptable |
| Below 3.6 | Needs Improvement |
Latency
Latency is the time it takes for voice packets to travel from the caller to the recipient.
High latency causes noticeable delays in conversations, making interactions feel unnatural.
Recommended Levels
- Below 150 ms – Excellent
- 150–200 ms – Acceptable
- Above 250 ms – Likely to impact conversation quality
Jitter
Jitter measures the variation in packet arrival times.
Excessive jitter can cause robotic voices, choppy audio, or gaps in conversations.
Most modern networks use jitter buffers to smooth packet delivery, but consistently high jitter still degrades call quality.