TP-Link Omada – VoIP / SIP Configuration Guide

Table of Contents

Overview Before you start Ports used by VoIP Configuration 1. Disable SIP ALG 2. Confirm outbound firewall behaviour 3. NAT considerations 4. QoS (important on busy links) 5. VLANs (if applicable) Good practice Troubleshooting Calls connect but no audio Calls drop after 30 seconds Phones won’t register Poor call quality

Overview

This guide covers how to configure TP-Link Omada routers (ER series / Omada SDN) for SIP-based VoIP services.

Out of the box, Omada works reasonably well, but there are a couple of settings that can interfere with SIP — mainly SIP ALG and traffic prioritisation. If those aren’t addressed, you may run into issues like one-way audio, unreliable registration, or poor call quality under load.

Before you start

You’ll need:

Access to the Omada Controller (or standalone router UI)
Admin credentials
SIP provider details (IP ranges if available)

If the site is behind another router or ISP device, check whether you’re dealing with double NAT — that’s a common source of problems.

Ports used by VoIP

SIP signalling: 5060 (UDP/TCP), sometimes 5061 (TLS)
RTP media: typically UDP 10000–20000

Both types of traffic must be allowed in and out — blocking either will break calls.

Configuration

1. Disable SIP ALG

In the Omada controller:

Settings → Transmission → NAT → ALG

Disable:

SIP ALG

Why this matters:
SIP ALG tries to modify SIP packets as they pass through the router. In practice, this often causes more harm than good — especially with hosted VoIP — by breaking NAT handling and audio streams.

2. Confirm outbound firewall behaviour

Omada doesn’t usually block outbound traffic by default, but it’s still worth checking.

Go to:

Settings → Firewall → Rules (LAN → WAN)

Make sure:

UDP 5060 is allowed outbound
UDP 10000–20000 is allowed outbound

If you’re working in a more locked-down environment, create explicit allow rules for these.

If your provider supplies IP ranges, it’s a good idea to restrict SIP traffic to those instead of leaving it open.

3. NAT considerations

Omada uses standard NAT (masquerade) by default.

That’s normally fine, but keep in mind:

Avoid double NAT where possible
If using another firewall upstream, make sure it isn’t also interfering (especially with SIP ALG)

For most hosted VoIP setups, no inbound port forwarding is required.

4. QoS (important on busy links)

If the connection carries general traffic (file transfers, backups, etc.), you’ll want to prioritise voice.

Go to:

Settings → Transmission → QoS

Enable QoS
Add a rule matching:
- UDP traffic
- RTP port range (10000–20000)

Set priority to:

High

This helps prevent jitter and packet loss when the link is under load.

5. VLANs (if applicable)

If phones are on a dedicated voice VLAN:

Make sure inter-VLAN routing isn’t restricting RTP
Apply QoS policies to the voice VLAN where possible

Good practice

If your ISP uses CGNAT, expect issues unless handled properly
Keep firmware up to date (Omada improves VoIP handling regularly)
Don’t rely on “auto VoIP optimisation” features — they’re rarely accurate

Troubleshooting

Calls connect but no audio

Usually RTP is being blocked or routed incorrectly.

Check:

RTP ports are allowed outbound
SIP ALG is definitely disabled
There isn’t another router upstream interfering

Calls drop after 30 seconds

Classic SIP ALG symptom.

Re-check:

SIP ALG is disabled on Omada
No upstream firewall is still running it

Phones won’t register

Work through the basics:

Can the router reach the SIP server (DNS / routing)?
Is UDP 5060 allowed outbound?
Is the WAN connection stable?

Poor call quality

Usually network-related.