Step-by-step: adding the trunk in 3CX

To add your 25-Line account to 3CX:

1. In the 3CX console go to SIP Trunks → Add SIP Trunk and choose Generic SIP Trunk (or Generic VoIP provider).
2. Enter the registrar/server sip.transcom.net.
3. Set Authentication to Register/Account based and enter your account user ID and password.
4. Set the number of Simultaneous Calls to 25 to match your channels.
5. Add your DID numbers to the trunk and set the main DID.
6. Create inbound rules routing each DID to the right destination (extension, digital receptionist, ring group or queue), and outbound rules sending external calls over the trunk.
7. Set the outbound Caller ID to a matching in-country DID so calls qualify for national rates.

Confirm the trunk shows Registered in the 3CX dashboard, then place a test call.