Proximus - SIP Trunk
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Proximus is the largest of Belgium’s telcos, and was previously known as Belgacom. They offer Business VoIP services under various names. At the moment the documentation below applies for:
- Proximus - Wireless Office Extended
- Proximus - Business Trunking with IMS services
Reference website: Proximus
Before configuring the SIP trunk it is required to go through the following checklist and make changes where necessary:
- NAT (when used) created to 3CX
- Firewall Checker passed
- Firewall SIP ALG checked and if present disabled
Further setup information can be found in our Academy: 3CX Academy Basic Course
Some providers gained support and compatibility with 3CX on a specific product version. It is advisable to always run the latest version of 3CX to ensure ongoing compatibility.
Minimum 3CX Version: 3CX Phone System 15.5 SP3
Below is a short overview of the provider's capabilities and services and whether they’re supported or not:
- CLNS (Clip No Screening): No
- Catch All Routing: Yes
- Fax T.38 support: Yes
- CLIR (Number Suppression): Yes
- DTMF via RFC 2833: Yes
- Codec Order: G711A, G729
- NAT Support: Yes
Configuring the Trunk with 3CX
The general instructions outlining how to add a new SIP Trunk to your 3CX installation can be found here.
Adding the Trunk
Go to “SIP Trunks” and select “Add SIP Trunk”
- Select Country: BE
- Select Provider in your Country: Proximus
- Main trunk number: This will have been provided to you by Proximus. You must enter the number in the International number format (e.g. +32xxxxxxxx)
- Press OK
Under the “General” tab in the “Trunk Details” section, enter the Primary IP given to you Proximus in the “Outbound Proxy” field. Make sure to leave the “Registrar” field unchanged.
Once you have done this, scroll to the top of the page and press OK.
Adding Additional DIDs
To associate all other DIDs/Numbers you have in your Proximus account with 3CX, go to the Management Console → SIP Trunks, double-click on your Proximus Trunk and go to the “DIDs” tab.
Here you should already see 1 entry that is the Main Trunk number you have set. Add all other DIDs/Numbers you have to the list in the International number format (e.g. +32xxxxxxxx) and press OK.
Creating Inbound Rules
Now that you have associated all your DIDs/Numbers with your SIP Trunk in 3CX, you can create Inbound Rules to set where calls will be routed when those numbers are called. Instructions on how to create Inbound Rules can be found here.
When configuring Proximus SIP Trunks in 3CX, all numbers should be entered in an International number format (e.g. +32xxxxxxxx), otherwise call routing will fail.
Disabling E.164 Processing
To avoid changing the format of the dialed number when using your Proximus Trunk, E.164 Processing must be disabled in 3CX. To do this:
- Open the 3CX Management Console and navigate to Settings → E.164 Processing.
- Make sure the “Process E164 Numbers” option is checked.
- From the “Select Country” drop-down, change the country to any other country except Belgium (preferably a country you will never dial to).
- Uncheck the “Process E164 Numbers” option.
- Press OK.
After this, 3CX will forward all numbers exactly as dialed by the users to the Providers.
Note: This is a global settings and will affect all outbound dialing regardless of which provider you will use.
Outbound Caller ID
Proximus Trunks do not support Clip No Screening, meaning that you can only present numbers that you have associated to your account. Those must be input in an International number format (e.g. +32xxxxxxxx).
Proximus Trunks allow outbound calls to be made when the dialed number is in any valid number format in Belgium. That means that they can be dialed in either National (e.g. 0xxxxxxxx) or International (e.g. +32xxxxxxxx) formats.
More information about how to create Outbound Rules and how they work can be found here.
Faxing over VoIP
Proximus Trunks do support faxing over VoIP using T.38 in bypass mode. This means that that if the source/sender of the fax is transmitting using T.38, then it will be delivered to your 3CX server with T.38 as well. If however the source is sending the fax over G.711 pass through, it will reach the 3CX server as is.
Dealing with Faxing issues
The built-in 3CX Fax Server which only acts as an incoming Fax Server, by default only supports T.38 faxing. This means that if a fax comes through your Proximus Trunk as G.711 pass through, it may fail, and this is likely as Proximus does not upscale G.711 to T.38 and it depends on the source of the fax.
If you are having issues receiving faxes, you could try enabling G.711 fallback on for your 3CX Fax Server. To do this:
- Access your Management Console and go to Settings → Fax Server.
- Check the option “Enable G.711 to T.38 Fallback” and press OK.
Important: Faxing over G.711 pass through, although being possible, can sometimes be unreliable as it is heavily influenced by network latency and audio quality between the 2 peers. Faxing being sent this way could have degraded quality. This is something outside of the control of 3CX.
T.38 should be preferred whenever possible.
Setting Up a Redundancy Trunk
Proximus may also provide an additional Backup Signalling server IP. This is for cases where the Proximus Primary Signalling IP may fail. The intended use is that all incoming and outgoing calls will first use the Primary Signalling IP and only upon failing should the Backup Signalling IP be used.
Before setting up the Redundancy Trunk
The first step would be to setup your Proximus Trunk as described earlier in this guide in section “Adding the Trunk” using the Primary Signalling IP. This also includes adding all the DIDs associated with your Trunk as described in section “Adding Additional DIDs” and then creating Inbound Rules for all your DIDs as described in section “Creating Inbound Rules”. It is best the above have been done before proceeding to setup your redundancy Trunk
How to set up the Redundancy Trunk
Once you have setup your Primary Proximus Trunk and tested that it works, all you need to do is repeat steps outlined in sections “Adding the Trunk”, “Adding Additional DIDs” and “Creating Inbound Rules” with one difference, instead of using the Primary Signalling IP, use the Backup/Secondary Signalling IP that you have been given by Proximus. You could also name your Backup Trunk slightly different so that you distinguish it, e.g. “Proximus - Backup”:
Using the Redundancy Trunk(s)
When creating Inbound Rules, you now need to create multiple rules for each DID/number, one for every Proximus Trunk you have created (Primary and Backup):
For your Outbound Rules, in order to make use of the backup trunk(s), all you need to do is make sure that you have set them as the subsequent “Route” options. Note that the Primary Trunk should always be set to “Route 1”:
Remarks / Limitations
3CX has successfully passed the official Proximus validation testing process. The following remarks / limitations were noted during the validation testing between 3CX and Proximus:
- Outbound calls made with a restricted caller ID will all get charged on the 3CX MCN (Main Company Number)
- In case of an incoming calls being redirected directly to an external number, the diverted call will get charged on the 3CX MCN.
- In case of a Blind Call Transfer, the transferred call will get charged on the 3CX MCN.
- On calls towards the emergency services, 3CX does not deal with the required calling / called party number manipulations (emergency prefix, ZIP code, EVN), therefore its use is restricted to mono-site configuration setups.