TryLearn More

Use SIP trunks, WebRTC & Apps

Slash your Phone Bill by 80%

Multiple Outbound Call Routes

On this topic:

Multiple Outbound Routes

Selecting/Skipping Routes

Early Media and Ringing

IP Based SIP Trunks (Peering)

3CX routes calls to SIP Trunks (outbound) based on criterias the administrator defines.

An overview of “Outbound Routes” are explained in our Academy. 

Each rule allows the administrator to set-up to 5 routes which 3CX can select in case a route failed to process the call.

However, when using multiple routes the following points should be taken into consideration:

Selecting/Skipping Routes

  • 3CX will select all available SIP Trunks and Bridges in order (1 to 5)
  • In the case a SIP Trunk is unregistered (red) it is skipped immediately
  • Ringing (180 or 183) does not define a successful call and another SIP Trunk might be selected or the hunt will end accordingly upon receiving the SIP message
  • In case a SIP Trunk returns any of the following “busy” SIP messages the next route will NOT be selected and a busy signal will be sent to the internal caller immediately:
  • 486 Busy Here
  • 600 Busy Everywhere
  • 1408 No Response (3CX internal error code)
  • A call is considered “successful” when the following call states are reached and no further route will be selected
  • 200 OK  (Called Party Answered)
  • Cancel (Calling Party ends the call before being connected)
  • A list of common error SIP status codes which will cause a switch to the next available line is stated at the end of this document

Early Media and Ringing

When using more than one route in a rule the processing of early media and ringing will change. As 3CX can not foresee that a selected route to the called party might still fail to another route, certain handling in the ringing state is altered in relation to early media processing (commonly SIP, 183 Ringing).

After receiving 183 ringing messages, which is normally used to pass country specific ringtones as an audio stream or early media info, such as “this call will cost $1 per minute”, these will be converted in 3CX to 180 and the “audio stream” will be dropped. Extensions can not hear the early media announcement and/or IP phones will play the devices ringing tone instead of the media stream provided by the provider.

IP Based SIP Trunks (Peering)

IP based providers (peering) have no registration and therefore it is not possible for 3CX to determine if the SIP trunk is up or not. The result is always “green” and 3CX will try for each call to select the line before skipping to the next route. This will result in an outbound call delay of 32s until route 2-5 is selected which cannot be overcome (or avoided).

List of SIP answers causing a switch to route 2-5:

400 Bad Request

401 Unauthorized

402 Payment Required

403 Forbidden

404 Not Found

405 Method Not Allowed

406 Not Acceptable

407 Proxy Authentication Required

408 Request Timeout

409 Conflict

410 Gone

411 Length Required

413 Request Entity too large

414 Request URI too long

415 Unsupported Media Type

416 Unsupported URI Scheme

420 Bad Extension

421 Extension Required

423 Interval too brief

433 Anonymity Disallowed

480 Temp Unavailable

481 Call Transaction does not exist

482 Loop Detected

483 Too many hops

484 Address Incomplete

485 Ambiguos

487 Request Terminated

500 Server Internal Error

501 Not Implemented

502 Bad Gateway

503 Service Unavailable

504 Server Timeout

505 Version Not Supported

513 Message Too Large

603 Decline

604 Does not exist anywhere

606 Not Acceptable