✔️Network Readiness & QoS

Ensure your network can support high-quality voice calls with Zoom Phone. This guide covers bandwidth requirements, QoS settings, and firewall configurations to prevent call quality issues.

⏱️ Estimated Time: 30–45 minutes

👤 Who's This For

Network Admins, IT Infrastructure Teams, System Administrators

💼 Use Case

Pre-deployment network validation, troubleshooting call quality issues, or preparing for large-scale Zoom Phone rollouts.

✔️ Prerequisites

Why Network Readiness Matters

⚠️ Poor network = poor calls: 90% of call quality issues stem from network problems, not Zoom. Get your network right and calls will be crystal clear.

Common issues from poor network prep:

  • Choppy or robotic audio

  • Dropped calls

  • One-way audio (can't hear caller or vice versa)

  • Echo and audio delays

  • Calls failing to connect

Bandwidth Requirements

Per User Requirements

Zoom Phone audio only:

  • Upload: 100 kbps per call

  • Download: 100 kbps per call

Typical usage scenario (including overhead):

  • 1 concurrent call per user = 150 kbps up/down

  • Add 20% buffer for network overhead

Calculate Your Total Bandwidth

Use this formula:

Example calculation:

  • 50 users, 30% on calls simultaneously

  • 50 × 0.30 = 15 concurrent calls

  • 15 × 150 kbps × 1.2 = 2.7 Mbps

💡 Pro Tip: Most offices need 3-5 Mbps dedicated for Zoom Phone. This is minimal for modern internet connections.

Steps to Prepare Your Network

1

Test Your Current Bandwidth

  • Run speed test from your office network (not personal devices)

  • Use https://speed.cloudflare.com or https://fast.com

  • Test during peak business hours

  • Minimum recommended: 25 Mbps down / 5 Mbps up (for small offices)

  • Verify upload speeds especially—voice traffic needs good upload

2

Configure Quality of Service (QoS)

  • QoS prioritizes voice traffic over less critical data

  • Configure on your router/firewall to prioritize Zoom traffic

  • Mark Zoom Phone packets with DSCP value: EF (46) for audio

  • Apply QoS to both inbound and outbound traffic

  • QoS prevents file downloads from degrading call quality

3

Open Required Firewall Ports

Allow these ports for Zoom Phone traffic:

Protocol
Ports
Purpose

UDP

8801-8810

Audio/video

TCP

443

HTTPS signaling

TCP

8801-8810

Backup if UDP blocked

  • Whitelist Zoom IP ranges (check Zoom documentation for current list)

  • Allow outbound connections to *.zoom.us domains

4

Disable SIP ALG (Application Layer Gateway)

  • SIP ALG on routers often causes call failures

  • Most routers have this enabled by default

  • Log into your router settings and disable SIP ALG

  • Common location: Advanced Settings > SIP ALG or NAT Helper

  • This fixes 80% of "calls won't connect" issues

5

Configure Network Settings

  • Enable consistent NAT (Network Address Translation)

  • Disable or configure VPN split tunneling for remote workers

  • For remote users, allow Zoom Phone to bypass VPN

  • Set router/firewall session timeout to at least 300 seconds

  • Disable deep packet inspection (DPI) for Zoom traffic if possible

6

Test Call Quality

  • Use Zoom's built-in network test: https://zoom.us/test

  • Make test calls between users

  • Monitor jitter (should be <30ms)

  • Monitor packet loss (should be <1%)

  • Check latency (should be <150ms)

Network Requirements Checklist

Remote Worker Considerations

Home network requirements:

  • Minimum 10 Mbps down / 3 Mbps up

  • Wired ethernet preferred over Wi-Fi

  • Modern router (5+ years old or newer)

Common remote worker issues:

  • Wi-Fi interference → Use 5GHz band or wired connection

  • Shared bandwidth → QoS on home router if available

  • VPN conflicts → Configure split tunneling

  • ISP throttling → Contact ISP if consistent issues

Provide remote workers:

  • Network requirements documentation

  • Speed test instructions

  • Recommended router settings

  • IT contact for network issues

💡 Quick Wins for Better Call Quality

Use wired connections when possible Ethernet is always more stable than Wi-Fi for voice calls.

Update router firmware Outdated firmware causes mysterious call issues. Update regularly.

Separate voice and data VLANs If your network supports it, this guarantees voice traffic priority.

Monitor network health Use tools like PingPlotter or Zoom's built-in analytics to catch issues early.

Plan for growth Today's 50 users might be 100 users next year. Size network accordingly.

🚀 Testing Your Network

Run these tests before going live:

1

Bandwidth Test During Business Hours

  • Use speed test tools from multiple locations

  • Test at 9am, 12pm, and 3pm (peak times)

2

Make Test Calls

  • Between internal users

  • To external numbers

  • From different locations (office, home, mobile)

3

Stress Test with Multiple Simultaneous Calls

  • Have 30-50% of users on calls at once

  • Monitor for quality degradation

4

Test Failover Scenarios

  • What happens if primary internet fails?

  • Do calls fail gracefully?

  • Is there automatic reconnection?

⚠️ Common Network Issues

See Details

Choppy/robotic audio → Usually packet loss or jitter. Check QoS settings and bandwidth.

One-way audio → Usually firewall or SIP ALG issue. Disable SIP ALG and check ports.

Calls drop after 30-60 seconds → NAT session timeout too short. Increase to 300+ seconds.

Can't make outbound calls → Firewall blocking outbound connections. Check port 443 and UDP 8801-8810.

Echo on calls → Network loop or acoustic issue. Check for duplicate audio sources.

🎯 What's Next

✨ Network ready! Your network now supports:

  • Adequate bandwidth for concurrent calls

  • QoS prioritization for voice traffic

  • Properly configured firewall rules

  • SIP ALG disabled

  • Tested call quality

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