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Network Readiness Guide

This guide helps you evaluate and prepare your network for cloud-based VoIP services by defining key components, protocols, and configuration best practices.

Key Network Components

Section titled “Key Network Components”
  • ISP & Modem: Your Internet connection (fiber, cable, DSL) terminates at a modem. When using a separate router/firewall, set the modem to Bridge Mode to avoid double NAT.
  • Router: Routes traffic between WAN and LAN. Configure static or dynamic routes appropriately.
  • Switch: Layer 2 aggregation devices for LAN connectivity; use VLANs to segment traffic if needed.
  • Bridge Mode: Puts a combo modem/router into modem-only mode, disabling its DHCP and NAT functions.

VoIP Protocols

Section titled “VoIP Protocols”
  • SIP (Port 5060/UDP): Handles call setup and teardown. Prioritize SIP traffic in your firewall/QoS rules.
  • RTP (Ports 10000–20000/UDP): Carries voice media. Reserve these ports for call audio.

How VoIP Works

Section titled “How VoIP Works”
  1. Registration: Devices register via SIP to the cloud to maintain reachability.
  2. Call Setup: SIP messages negotiate media ports (RTP).
  3. Media Exchange: RTP streams voice data once the call is active.
Example SIP Registration Flow Call Setup Flow Diagram

Bandwidth & Call Paths

Section titled “Bandwidth & Call Paths”
  • G.711 Codec: ~87.2 kbps each direction per call. Use this to calculate needed upstream/downstream capacity.
  • Call Paths: Only calls to/from the PSTN consume prepaid call paths; internal calls within the cloud do not.
Bandwidth vs Call Path Usage

Performance Metrics

Section titled “Performance Metrics”
  • Packet Loss: Aim for ≤0.75%.
  • Jitter: ≤50 ms.
  • Latency: ≤150 ms.
  • MOS: ≥3.6 for acceptable call quality.

Recommended QoS Settings:

  • Enable QoS, prioritize UDP 5060 (SIP) and 10000–20000 (RTP).
  • Disable SIP ALG on routers.

Network Separation Strategies

Section titled “Network Separation Strategies”

  1. Physical Separation: Dedicated voice and data networks with separate ISP links.

    Separate Voice and Data Networks Converged at Layer 3 with QoS

  2. Logical Separation: Single LAN with VLANs for voice/data. Dual ISP or single ISP with VLAN tagging.

    VLAN-Based Separation with Dual ISP VLAN Separation on Single ISP

  3. Flat SOHO Networks: Use QoS router; right-size ISP bandwidth.

    Flat Network Configuration Flat Network with QoS

Configurations to Avoid

Section titled “Configurations to Avoid”

Avoid multiple NAT devices or chained routers. Always use switches for additional LAN ports, and ensure a single NAT boundary.

Chained Routers to Avoid Multiple NAT Devices Issue

Troubleshooting Tips

Section titled “Troubleshooting Tips”
  1. Check SIP Registration: Verify device status via phone UI or PBX portal.
  2. Confirm Reachability: Look for offline indicators in the SIP peer status.
  3. Validate Network Config: Ensure single NAT, correct QoS, and bridge mode on modems.
  4. Isolation Testing: Move a device to a known-good network to isolate issues.