Configuring a Swisscom Enterprise SIP with 3CX

Swisscom Logo

Step 1: Preparation

A prerequisite is that a Lan2Lan VPN connection has been established between your network and the Swisscom SBC. Refer to the Swisscom documentation on how to create this connection. To validate the SBC can be reached, ping the SBC IP given to you by Swisscom to determine connectivity.

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 as E164. For example +41123456789

Step 3: Special Configuration

  1. NAT installation:The implementation of the Swisscom SBC does not require a NAT device in the traditional sense for the use of this SIP trunk. However, the correct VPN ACL must be set.
  2. Fax:Fax using T.38 is supported using the 3CX Fax server, but no fallback to G711 Fax is possible. Implementations with analog fax devices via ATA converters (FXS) must be configured as pass-through with T38 and G711. This configuration of the relevant ATA is to be done by the ATA manufacturer itself.
  3. E164 Disable:You must also disable the automatic conversion of E164 numbers in 3CX. To do this, go to “Admin ⇒ Advanced ⇒ E164” and uncheck “Process E164 Numbers”.


Conditions and limitations

Swisscom “Enterprise SIP” was implemented in version 15 of 3CX Phone System and was retested with version 16,18 and 20. The implementation is carried out via an SBC in your Swisscom company network, which is connected via a Lan2Lan (MPLS) VPN connection. This is provided by Swisscom for the term of the agreement. Setup of the Lan2Lan coupling is not part of this guide. 3CX must be installed on the standard SIP port 5060.

3CX does not support the geo position emergency call mode defined by Swisscom. The emergency / emergency call center is selected from the emergency call origin. Use of history info is currently not implemented by 3CX. Outgoing connections are identified and billed on the main number, as configured on the “CLIP special Arrangement” or CLIR connection.

About Swisscom

Swisscom’s history dates back to 1852 and the company has since grown to be the leading telecommunications provider in Switzerland. Also offering its services in Italy, the company offers a wide range of internet, TV, Cloud and telephony solutions. Swisscom ensures a simple, reliable and secure SIP trunking service for use with your 3CX PBX

Last Updated

This document was last updated on 15 March 2024

https://www.3cx.com/docs/sip-trunk/swisscom-enterprise-sip-switzerland/