In this article, you can find answers to the most popular questions about SIP PBX connection.

If I connect SIP PBX, can I make outgoing calls via Bitrix24 Telephony provider (Voximplant)?

Yes, you can select a rented number as a default number for outgoing calls. Click Telephony > Connection > Configure telephony > Telephony settings. In this case, outgoing calls will be made via Voximplant and inbound calls will be still processed using your PBX.
Important: if you select your PBX as a default number for outgoing calls, you have 60 free minutes to make outgoing calls. When you run out of free minutes, you need to buy a SIP connector to make outgoing calls or select a rented number as a default number for outgoing calls.

I have connected my office PBX, but I cannot see clients phone numbers in Bitrix24. How to fix it?

Maybe you have custom configuration, try to open extensions.conf and replace
1,Set(CALLERID(name)=${CALLERID(num)}) n,Set(CALLERID(num)=sip1) n,Dial(SIP/voximplant/${EXTEN})
Important: instead of sip1, specify the login from office PBX settings page.

When configuring SIP PBX connection I see "Please wait for connection to complete before accepting incoming calls" message and get an "error" status. What does it mean?

You need to copy an error code and error text and send to your SIP PBX provider to fix this problem.

My Telephony balance is getting charged for outgoing calls, although I've paid for SIP connector. Why?

You get charged for outgoing calls if you're using a rented number for outgoing calls.

You need to click Telephony > Connection > Configure telephony > Telephony settings and select your PBX as a Default number for outgoing calls:

I use SIP connector. When getting an inbound call to my PBX, caller's phone number is not displayed correctly. How to fix it?

Looks like your SIP PBX provider uses non-standard protocol. Please contact your SIP PBX provider and ask to set SIP parameters correctly.

I've connected my SIP PBX, but when trying to make an outgoing call I get a message saying that I need to rent a number. Why?

Make sure that you've selected SIP PBX as a default number for outgoing calls in Telephony > Connection > Configure telephony > Telephony settings.

Also, make sure that your PBX is specified as a number for outgoing calls for the specific user (Telephony > Connection > Configure telephony > Telephony users). Read more in the article - Specify a number for outgoing calls for a user.

Is it possible to use TCP as a transport protocol for SIP connection?

Yes, you can use TCP as a transport protocol instead of UDP. UDP is more suited to fast communications such as voice and video streaming. But sometimes using TCP solves problems with unstable connection.

To use TCP, add the parameter ;transport=tcp to the server address in the connection settings:

  • Most of the SIP PBXs don't support TCP, so we strongly recommend to contact your PBX provider to find out if it's possible to use TCP.

  • Bitrix24 supports TCP only for calls via SIP connector.

Can I use a REST telephony application and a SIP connection at the same time?

We do not recommend to use the application and SIP connection from one provider at the same time. It can cause errors: duplicate calls in the call details, no "Answer" button, etc.
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