SIP trunks

SIP trunks enabling makes it possible to make and forward calls to mobile numbers. For now, the Link works only with the Twilio platform. You can add multiple trunks on a server and assign them to groups.

For this feature, you must have the Link version with SIP and the purchased license with enabled SIP trunks. 

How to configure SIP trunks functioning

  1. Register with Twilio.  

  2. Enter a reliable mobile number and verify it via SMS. It is used as CallerID.

  3. Upgrade you account. It must not be Trial, as you will have to verify each called number manually. Also, you account must have positive balance. 

  4. Buy a number to make calls. 

Usually, you are recommended to buy a number as a part of your registration process. 

You can check whether you have purchased number or not in the Phone Numbers > Active Numbers section.


If there are no numbers, go to the Buy a number section. Select the country where the number is registered, its capabilities, and click Buy in the number line you are going to get.

5. Open Elastic SIP Trunks > Manage > Trunks and create SIP Trunk. The following settings are required for the trunk: 

  • disabled call recording;

  • enabled SymmetricRTP;

  • subdomain for SIP Trunks (in the Termination SIP URI section); 

  • IP access contol list: media servers and SIP proxies IP addresses (in the Authentication section). Only these IP addresses will be able to communicate with the trunk;

  • credentials with which entered media server will call (in the Credential lists section);

  • CallPerSec values for regions;

6. In the Numbers section, add an exesting (previously) created number for the trunk. 

7. Select available for calls counties in the Voice > Settings > Geo permissions section.

8. Open General setting of the Link server and go to the SIP trunks tab. 

9. Click plus icon (in the left low corner).

10. Enter all required data: 

  • trunk name;

  • termination SIP URI (indicated in the step 5);

  • outgoing number (number that the mobile user will see when he receives a call, CallerID);

  • trunk login from twilio;

  • trunk password from twilio.

11. Select group(s) for which this trunk will work. Users of these groups will use the trunks assigned to them when calling mobile numbers. It is possible to assign different trunks for root group(s) and subgroups. 

Only one trunk can be assigned to one group. If you select a group with assigned another trunk, then it will be replaced with the current one. Different trunks can be used for root group and its subgroups.


In case when root group and subgroups have different trunks, the closest trunk to the user will be used for the call. For example, for Building #1 and Test residental complex different trunks are assigned. So, for a user from Building #1, tunks assigned to the Building #1 group will be used, as its the closest.     

12. Save configurations.