Configuring a A1 Bulgaria Trunk with 3CX

A1 Bulgaria logo

Step 1: Server Configurations

A1 Bulgaria trunks require a direct connection between your 3CX server and A1 Bulgaria via VPN. To achieve this, a separate NIC is required on the 3CX server. It must be configured with a local IP address provided by A1 Bulgaria and a static route to route all traffic through the correct NIC. All information will be provided to you by A1 Bulgaria upon delivery of your trunk. Please note that the NIC must NOT have a default gateway configured.

Adding Static Routes

You must add some static routes so that the traffic from the 3CX server towards the A1 Bulgaria servers is routed through the correct NIC.

Windows: Open a command prompt using the “Run as Administrator” option and run the following command:

route -p add [A1  Registrar IP] mask [IP mask] METRIC 1 [Gateway IP]

Debian: The most common way of configuring Static Routes is by adding them to /etc/network/interfaces by creating a static route under the dedicated NIC using the following format:

 

up ip route add [A1 Registrar IP] via [Gateway IP] dev [NIC ID] src [NIC IP]

Example: up ip route add 213.226.61.0/24 via 10.251.222.113 dev ens224 src 10.251.222.115

Step 2: Configuring your SIP Trunk with 3CX

  1. Go to the 3CX Web client and follow the guide on how to configure a SIP trunk.
  2. Not compatible with Hosted by 3CX.
  3. Enter the main trunk number in the international format (e.g. 359875559473).
  4. Add the IP address of the dedicated NIC under the “Select which IP to use in 'Contact' (SIP) and 'Connection'(SDP) fields” field in the “Options” section of the trunk.
  5. Only numbers associated with your account can be presented as Outbound Caller ID.

About A1 Bulgaria

A1 Bulgaria is a part of the larger A1 group which operates throughout several countries in Eastern Europe as well as Austria. They are one of the leading digital services and telecommunications providers in Bulgaria, with a portfolio of services that includes fixed and mobile telephony, internet, business software, infrastructure, security and more. The A1 business SIP trunk is a secure, reliable solution which offers additional features for flexibility and easy management. The A1 SIP trunk is now available for selection from within the management console.

Last Updated

This document was last updated on 30 June 2023

https://www.3cx.com/docs/sip-trunk/a1-bulgaria/