Connection comparison
| Method | Authentication | Static IP | Best fit |
|---|---|---|---|
| SIP registration | Username and trunk password | Not required | Most PBXs and applications |
| SIP peering | Customer public IPv4 address | Required | Stable production PBX, SBC or softswitch |
| IAX2 registration | Username and trunk password | Not required | Asterisk, FreePBX and compatible systems |
| Built-in platform profile | Depends on selected template | Depends on platform | Supported AI voice and communications platforms |
SIP registration
The customer system registers with sip.sipflex.co.uk using the number or username and separate trunk password shown in the portal. This is the broadest default and normally works behind NAT without requiring a fixed public address.
SIP peering
The customer public IPv4 address identifies the connection. Peering suits systems with a stable address and deliberate firewall policy. Configure the address in the Sipflex profile and accept provider traffic only from the documented Sipflex source.
IAX2 registration
IAX2 is a first-class option for customers who deliberately use Asterisk, FreePBX or another compatible implementation. Signalling and media share the IAX2 protocol and host iax.sipflex.co.uk.
Built-in platform profiles
For supported AI voice platforms, the Sipflex portal can pre-populate provider-side routing details that match the selected service. The profile is a SIP template—not an account integration or endorsement.