Before you start
Sign in to the Sipflex portal and open the trunk you want to connect. Keep the profile, phone number or username and account-specific credentials visible while you configure your system.
- FreePBX 17 administrator access
- A Sipflex trunk username and separate trunk password
- A destination for inbound calls
- A backup of the FreePBX configuration
Use the current Sipflex endpoints.
The SIP registrar is sip.sipflex.co.uk and the IAX2 host is iax.sipflex.co.uk. Usernames and passwords remain account-specific and are shown in your portal.
Configure the connection
- Open Connectivity → Trunks and choose Add Trunk → Add SIP (chan_pjsip) Trunk.
- Give the trunk a clear name such as Sipflex.
- On pjsip Settings → General, enter the trunk username as Username and Authentication Username, then enter the trunk password.
- Set SIP Server to sip.sipflex.co.uk and SIP Server Port to 5060 for UDP/TCP or 5061 for TLS.
- Set Authentication to Outbound and Registration to Send.
- On Advanced, select RFC4733/RFC2833 DTMF, disable direct media, and allow alaw/ulaw or the supported codecs you require.
- Submit and Apply Config, then create an outbound route using the Sipflex trunk.
- Create inbound routes for every full Sipflex number delivered to the trunk.
| FreePBX field | Value |
|---|---|
| Username | Sipflex trunk username |
| Auth username | Sipflex trunk username |
| Secret | Sipflex trunk password |
| SIP server | sip.sipflex.co.uk |
| Port | 5060 / 50600, or 5061 for TLS |
| Authentication | Outbound |
| Registration | Send |
| Context | from-pstn or your restricted inbound context |
| DTMF | RFC4733 / RFC2833 |
| Direct media | No |
Additional numbers
Add other Sipflex numbers as FreePBX inbound routes; they do not require separate registrations.
Verify the service
- Confirm the trunk is registered or that the correct public peer IP is saved in the Sipflex portal.
- Place an outbound test call and check the caller ID presented.
- Call the Sipflex number from another network and confirm it reaches the expected inbound context or route.
- Check two-way audio and RFC4733/RFC2833 DTMF.
Support scope
We can check Sipflex credentials, registration state and provider-side call routing. Your PBX, device, firewall, dial plan and application remain your responsibility.