Prepare the Sipflex peer
- Sign in to the Sipflex portal and open Voice → Profiles.
- Select the SIP peering / IP-authenticated connection type.
- Add the fixed public IPv4 address of your PBX, SBC or application.
- Add a secondary address only when it is a genuine, controlled failover destination.
- Save the profile before sending traffic.
Peer settings
| Setting | Value |
|---|---|
| Sipflex SIP target | sip.sipflex.co.uk |
| Sipflex signalling/media address | 52.56.188.70/32 |
| Authentication | Source-IP based; no trunk username/password |
| SIP ports | UDP/TCP 5060 or 50600; TLS 5061 |
| DTMF | RFC2833 / RFC4733 telephone-event |
| Packet time | 20 ms |
Firewall rules
Restrict inbound rules to the current Sipflex network address. Do not expose SIP or RTP broadly to the public internet.
| Source / destination | Protocol | Port(s) | Purpose |
|---|---|---|---|
52.56.188.70/32 | UDP | 1024–50000 | RTP audio when using UDP or TCP SIP transport |
52.56.188.70/32 | UDP | 5060, 50600 | SIP signalling over UDP |
52.56.188.70/32 | TCP | 5060, 50600 | SIP signalling over TCP |
52.56.188.70/32 | TCP | 5061 | TLS signalling |
Current Sipflex address
Use 52.56.188.70/32 in provider allow-lists, peer matching and firewall rules.
Media and security
- Allow only the codecs you need: PCMA, PCMU, G.722 or G.729a
- Use 20 ms audio packetisation
- Keep media anchored through the PBX or SBC unless you have deliberately designed direct media
- Accept SIP only from the Sipflex address
- Prevent unauthenticated relay from internal or external sources
Do not create an open relay.
IP authentication identifies the carrier side of the trunk. Your own endpoints and users must still be authenticated and restricted by your PBX or SBC.
Verify the peer
- Confirm your public IP is saved correctly in the Sipflex portal.
- Place an outbound E.164-formatted test call through
sip.sipflex.co.uk. - Call each Sipflex number routed to the peer to verify inbound matching.
- Confirm two-way audio, DTMF and authorised caller ID.
- Test the secondary route separately if you configured failover.
Support scope
Sipflex can confirm the account profile and provider-side routing. Your public IP, firewall, SBC, PBX and failover design remain under your control.