SIP compatibility and PBX checks
Understand SIP exchanges, errors and useful PBX connection checks.
BeAI uses SIP to establish and end calls. Signalling corrections apply to manual connections, provisioning and BeAI Numbers without additional bot configuration.
Supported behaviour
Requests repeated after packet loss belong to the same exchange and must not create additional calls. Registration renewal follows the expiry granted by the PBX. BeAI also handles INVITEs without an initial audio offer and session changes during a call, as used by 3CX and other PBXs.
Signalling supports UDP and TCP. Large requests may require TCP, so the firewall must allow the transport agreed with your administrator. TLS requires platform and operator configuration with valid certificates. A rejected secure connection is not silently replaced by an insecure connection. Encrypted signalling does not imply encrypted audio.
Provisioning update notifications remain supported. Credit, bot permissions and pricing rules do not change with transport.
Understanding errors
| SIP response | What to check |
|---|---|
| 400 | The PBX message is incomplete or malformed. |
| 401 or 407 | Authentication challenges are normal; repeated failures require checking the account and secret. |
| 405 or 501 | The requested operation is unavailable. |
| 415 | The content type or encoding is unsupported. |
| 420 | The PBX requires an unsupported SIP extension; review mandatory options. |
| 481 | The dialog or transaction no longer exists, or its identifiers do not match. |
| 503 or no response | Check PBX availability, transport and network rules. |
Lost responses can cause normal retransmissions. A call that remains unacknowledged is eventually terminated to avoid leaving a stuck session.
Checking a connection
After changing the PBX or network, check registration and OPTIONS in the bot status. Test incoming and outgoing calls, a transfer, audio in both directions and hangup. The platform connects BeAI Numbers automatically; administrators can inspect the runtimes serving the bot.
When contacting support, provide the time, bot and observed outcome without passwords or SIP secrets. SIP support does not guarantee compatibility with every PBX extension.
See Choose bot telephony and Get a BeAI Number.