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Overview

VPNs provide valuable privacy and security benefits but can sometimes interfere with VoIP services like Quo, formerly OpenPhone. Understanding how to configure VPN settings properly ensures you maintain both privacy and reliable phone functionality.
Most VPNs work with Quo without additional configuration. Issues typically arise from port blocking or traffic filtering that affects voice communication.

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Understanding VPN and VoIP interaction

Common interference points:
  • Port blocking: VPNs may block ports used for voice traffic
  • Traffic filtering: Some VPNs filter UDP traffic required for calls
  • Latency introduction: VPN routing can add delay to real-time communication
  • Bandwidth limitations: VPN overhead may reduce available bandwidth
Quo’s VoIP requirements: Quo uses RTP (Real-time Transport Protocol) for voice media, which requires:
  • Specific port ranges for optimal performance
  • Low-latency network connections
  • Unrestricted UDP traffic flow
  • Adequate bandwidth for voice quality
Most VPNs work with Quo without additional configuration. Issues typically arise from port blocking or traffic filtering that affects voice communication.
Balancing security and functionality: You can maintain privacy while ensuring reliable phone service by:
  • Selective VPN usage: Disable VPN only for Quo traffic
  • VPN configuration: Adjust settings to allow VoIP traffic
  • Alternative privacy measures: Use other security practices
  • Network optimization: Configure both VPN and Quo optimally
Best practices:
  1. Use split tunneling to exclude Quo traffic
  2. Choose VPN servers geographically close to you
  3. Select VPN protocols optimized for real-time traffic
  4. Consider using VPN only when not making calls
Symptoms of VPN conflicts:
  • Calls failing to connect when VPN is active
  • Poor call quality with VPN enabled
  • One-way audio issues during calls
  • Connection establishment errors
  • Inability to receive incoming calls
5-minute diagnostic test:
  1. Document the issue: Note specific problems with VPN active
  2. Disable VPN temporarily: Turn off VPN completely
  3. Test Quo functionality: Make and receive test calls
  4. Compare performance: Note any improvements without VPN
  5. Re-enable VPN: Turn VPN back on to confirm issue returns
Results interpretation:
  • Works without VPN = VPN is blocking Quo
  • Still has issues = Problem is not VPN-related
  • Partially works = VPN configuration needs adjustment
Call connection failures:
  • VPN blocking outbound connections to Quo servers
  • Firewall rules preventing voice traffic
  • Geographic restrictions affecting service access
  • DNS routing issues with VPN servers
Audio quality issues:
  • Increased latency causing delayed audio
  • Packet loss through VPN routing
  • Bandwidth throttling affecting voice quality
  • RTP traffic filtering or modification
Notification and connectivity problems:
  • Push notification blocking through VPN
  • Persistent connection interference
  • WebSocket connection disruption
  • Real-time protocol filtering
If calls work but quality is poor, your VPN is allowing traffic but adding too much latency. Try a closer VPN server.

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VPN configuration solutions

Port ranges to allow:
  • Voice traffic ports: 10,000 - 20,000
  • Protocol: UDP (User Datagram Protocol)
  • Direction: Both inbound and outbound
  • Priority: High (for QoS-enabled networks)
IP address ranges to whitelist:
  • Primary range: 54.172.60.0 - 54.172.61.255
  • Secondary range: 34.203.250.0 - 34.203.251.255
  • Protocol: Both TCP and UDP
  • Purpose: Quo server communication
Quo uses RTP for voice media services. Filtering the specified port ranges can cause significant service degradation or complete call failures.
Additional requirements:
  • DNS resolution must work properly
  • WebSocket connections on port 443
  • Standard HTTPS traffic allowed
Step-by-step setup:
  1. Split tunneling: Enable split tunneling feature
  2. App exclusions: Add Quo to excluded applications
  3. Protocol selection: Use IKEv2 or OpenVPN UDP for better VoIP performance
  4. Server selection: Choose geographically close servers
ExpressVPN specific settings:
  • Settings → General → Split tunneling → Manage connection on a per-app basis
  • Add Quo to “Do not allow selected apps to use the VPN”
  • Settings → Protocol → Select IKEv2 or OpenVPN UDP
  • Avoid “Auto” protocol selection for consistent performance
Step-by-step setup:
  1. Split tunneling: Configure bypass for Quo
  2. CyberSec: Disable if causing connection issues
  3. Protocol: Select NordLynx or OpenVPN UDP
  4. Specialty servers: Avoid P2P servers for VoIP traffic
NordVPN specific settings:
  • Settings → Split tunneling → Enable → Add Quo
  • Settings → CyberSec → Disable (if experiencing issues)
  • Settings → VPN protocol → NordLynx (fastest) or OpenVPN UDP
  • Use regular servers, not Double VPN or Onion Over VPN
Step-by-step setup:
  1. Bypasser: Add Quo to bypasser list
  2. Protocol: Use WireGuard or IKEv2
  3. CleanWeb: Disable if affecting connections
  4. MultiHop: Avoid for VoIP to reduce latency
Surfshark specific settings:
  • Settings → VPN settings → Bypasser → Route via VPN → Add Quo to bypass
  • Settings → Advanced → Protocol → WireGuard or IKEv2
  • Settings → CleanWeb → Disable if having connection issues
  • Avoid MultiHop servers for voice calls
Enterprise requirements:
  • IT department coordination: Work with network administrators
  • Policy exceptions: Request Quo-specific allowances
  • QoS configuration: Prioritize voice traffic in corporate policies
  • Firewall rules: Add exceptions for Quo IP ranges and ports
Information for IT teams:
Service: Quo VoIP
Ports required: UDP 10000-20000 (RTP media)
IP ranges: 54.172.60.0/23, 34.203.250.0/23
Protocols: SIP, RTP, WebSocket
DNS: Must resolve *.openphone.co
Business continuity options:
  • Alternative access methods: Configure backup connectivity options
  • Mobile data fallback: Use cellular data when VPN blocks VoIP
  • Dedicated VoIP networks: Consider separate networks for voice traffic
  • Policy documentation: Maintain records of required configurations

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Advanced optimization

UDP traffic prioritization: VoIP relies heavily on UDP for real-time communication:
  • Disable UDP filtering: Ensure VPN doesn’t block UDP packets
  • Buffer settings: Optimize VPN buffer sizes for real-time traffic
  • Packet prioritization: Configure QoS to prioritize voice packets
  • MTU optimization: Adjust Maximum Transmission Unit for efficient packet delivery
DNS and routing optimization:
  • DNS servers: Use reliable DNS servers (8.8.8.8, 1.1.1.1)
  • Route optimization: Choose VPN servers with optimal routing to Quo
  • Geographic proximity: Select VPN endpoints close to your location
  • Carrier compatibility: Ensure VPN doesn’t interfere with carrier routing
Technical settings:
MTU: 1400-1450 (reduce from default 1500)
DNS: 8.8.8.8, 8.8.4.4 (Google) or 1.1.1.1, 1.0.0.1 (Cloudflare)
Protocol: UDP preferred over TCP
Buffer: Minimize to reduce latency
Latency reduction checklist:
  • Server selection: Choose geographically closest VPN servers
  • Protocol optimization: Use fastest VPN protocols (WireGuard, IKEv2)
  • Connection method: Prefer UDP over TCP for VPN connections
  • Concurrent connections: Limit other high-bandwidth activities during calls
Bandwidth management:
  • Speed testing: Verify adequate bandwidth with VPN active
  • Traffic shaping: Configure VPN to prioritize real-time traffic
  • Compression settings: Disable unnecessary compression that adds latency
  • Connection monitoring: Track performance metrics during calls
Target metrics for good call quality:
  • Latency: <150ms (excellent), <300ms (acceptable)
  • Jitter: <30ms
  • Packet loss: <1%
  • Bandwidth: 100kbps minimum each direction

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Alternative solutions

Application-level privacy: Instead of routing all traffic through VPN, consider:
  • Browser VPN extensions: Protect web browsing only
  • Specific app VPNs: Route only sensitive applications through VPN
  • Time-based VPN usage: Enable VPN only when not using Quo
  • Network-specific policies: Use VPN on public networks, direct connection at office
Device-level security without VPN:
  • Firewall configuration: Enable device firewalls for protection
  • DNS over HTTPS: Use secure DNS without full VPN
  • Encrypted messaging: Use encrypted communication apps
  • Regular updates: Keep all software current for security patches
Privacy tools that work with Quo:
  • NextDNS or Cloudflare DNS for privacy
  • Local firewall applications
  • Browser privacy extensions
  • Encrypted email services
What is split tunneling: Routes only specific traffic through VPN while other traffic goes directly to internet.Configuration approaches:
  • Whitelist approach: Only route necessary traffic through VPN
  • Application exclusions: Exclude VoIP and real-time applications
  • Geographic routing: Route only geographically sensitive traffic
  • Performance monitoring: Track which applications benefit from VPN
Recommended split tunnel setup:
  1. Enable split tunneling in VPN settings
  2. Add Quo to bypass/exclusion list
  3. Include other real-time apps (video conferencing)
  4. Keep sensitive apps routed through VPN
  5. Test configuration with calls
Security considerations:
  • Quo traffic will not be encrypted by VPN
  • Calls still encrypted by Quo’s security
  • Balance security needs with functionality
  • Consider network trust level

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Specific problem solutions

Diagnostic steps:
  1. Latency testing: Measure round-trip time with and without VPN
  2. Server switching: Try different VPN server locations
  3. Protocol testing: Test different VPN protocols for best performance
  4. Bandwidth verification: Ensure adequate speed for voice calls
  5. QoS configuration: Implement traffic prioritization
Quick fixes for quality issues:
  • Switch to closest VPN server (same country/state)
  • Change VPN protocol to WireGuard or IKEv2
  • Disable VPN encryption acceleration features
  • Reduce VPN encryption level if possible
  • Use split tunneling to bypass VPN for Quo
Expected latency impact:
  • Local VPN server: +20-50ms
  • Cross-country server: +50-150ms
  • International server: +150-300ms (poor quality likely)
Common causes with VPN:
  • NAT traversal: VPN breaking NAT hole punching
  • Firewall rules: Blocking return audio path
  • Port forwarding: Asymmetric port handling
  • STUN/TURN: Connectivity helper protocols blocked
Resolution steps:
  1. Enable split tunneling for Quo
  2. Check VPN firewall isn’t blocking UDP ports 10000-20000
  3. Disable VPN’s built-in firewall temporarily
  4. Try different VPN protocol (some handle NAT better)
  5. Contact VPN support about SIP/VoIP compatibility
One-way audio is often caused by strict NAT or firewall rules in the VPN that block the return audio stream.
Call setup troubleshooting:
  1. Signaling path: Verify SIP signaling can reach Quo servers
  2. Authentication: Ensure VPN doesn’t interfere with account verification
  3. DNS resolution: Confirm Quo servers resolve correctly
  4. Timeout settings: Adjust VPN timeouts for real-time requirements
Common fixes:
  • Temporarily disable VPN to confirm it’s the cause
  • Add Quo to VPN bypass/split tunnel list
  • Try different VPN server in same region
  • Check if VPN blocks VoIP intentionally (some do)
  • Use mobile data instead of VPN-protected WiFi
VPN features to disable:
  • Kill switch (during testing)
  • DNS filtering/AdBlock features
  • Threat protection
  • Multi-hop connections
Causes of intermittent problems:
  • Connection stability: VPN connection dropping/reconnecting
  • Automatic reconnection: Disrupting active calls
  • Server load: VPN server congestion at peak times
  • Failover behavior: VPN switching servers mid-call
Stabilization steps:
  1. Disable VPN auto-reconnect during calls
  2. Select specific server instead of “auto” selection
  3. Monitor VPN connection stability
  4. Use wired connection instead of WiFi
  5. Set VPN to use TCP instead of UDP (more stable)
Long-term solutions:
  • Upgrade to business VPN plan with SLA
  • Use dedicated VPN server if available
  • Configure static VPN connection
  • Consider SD-WAN for business use

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Best practices

Recommended setup:
  1. Enable split tunneling: Route only necessary traffic through VPN
  2. Server selection: Choose closest geographic server
  3. Protocol choice: Use WireGuard or IKEv2 for best performance
  4. Connection type: UDP over TCP when available
  5. Regular testing: Weekly quality checks
Configuration checklist:
  • ✓ Split tunneling enabled with Quo bypassed
  • ✓ Closest VPN server selected (check latency)
  • ✓ Fast protocol configured (not OpenVPN TCP)
  • ✓ Kill switch disabled for Quo
  • ✓ DNS properly configured
  • ✓ Ports 10000-20000 UDP allowed
Monitoring recommendations:
  • Test call quality weekly
  • Document working configurations
  • Monitor latency to VPN servers
  • Track any quality degradation
  • Update VPN client regularly
Scenarios requiring direct connection:
  • Critical business calls: Important meetings or customer calls
  • High-quality requirements: Calls requiring optimal audio quality
  • Low-latency needs: Real-time collaboration or emergency communications
  • Troubleshooting situations: When diagnosing call quality issues
Quick VPN toggle strategy:
  1. Set up VPN client with hotkey for quick disable
  2. Disable VPN just before important calls
  3. Re-enable immediately after call ends
  4. Use calendar reminders for scheduled calls
  5. Consider automated scripts for regular call times
Alternative approaches:
  • Use separate device for Quo without VPN
  • Configure network-based VPN bypass for Quo device
  • Use mobile data for calls while computer stays on VPN
  • Set up dedicated “calling hours” without VPN

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Support and escalation

Escalate to Quo support when:
  • VPN configuration doesn’t resolve issues
  • Need help with port requirements
  • Unclear if issue is VPN or Quo
  • Business operations affected
Contact VPN provider when:
  • Need help configuring split tunneling
  • VPN blocks VoIP intentionally
  • Protocol or server recommendations needed
  • Corporate VPN policy questions
Support coordination tips:
  • Start with VPN provider for configuration
  • Contact Quo if VPN changes don’t help
  • Provide test results to both teams
  • Document all configuration attempts
Submit Quo support request at: support.openphone.com

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Additional resources

Need assistance? Submit a support request at support.openphone.com with your VPN configuration details and specific connectivity issues for personalized troubleshooting help.
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