BT SIP-T Trunk
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BT SIP Trunk is a cost effective SIP Trunking solution for businesses across the UK. With no compromise on quality of service and increased flexibility, compared to traditional phone lines, BT offers a reliable, affordable and secure SIP Trunking service.
Website source: www.bt.com
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 SP4
Below is a short overview of the provider's capabilities and services and whether they’re supported or not:
- CLNS (Clip No Screening): No, only DID’s provided by BT can be used for outbound calling
- Catch All Routing: Yes
- Fax in T38: No
- CLIR (Number Suppression): Yes
- DTMF via RFC 2833: Yes
- Codec Order: G711U, G711A, G729, G722
- NAT Support: Yes
- One SIP Trunk per SIP Realm/Domain provided by BT
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
More specifically please make sure that the correct template is selected when adding the trunk to the phone system. The template can be found under UK in the “Add SIP Trunk” menu. Choose the BT HSIPT trunk. You will be asked for the main trunk number which should be in international format (e.g. 448135791691). Once you click the OK button the general settings page will open where the registration details can be configured
You will need to to add your specific Domain name provided by BT in the “Registrar/Server/Gateway Hostname or IP” field.
You need to use the main trunk (or pilot) number as “Authentication ID” and enter it in an international format (e.g. 448135791691). The Authentication Password is provided by BT.
The Authentication Username provided by BT must be entered under “3 Way Authentication / “Authentication Password”.
Adding Additional DIDs
To associate all other DIDs/Numbers you have in your BT account with 3CX, what you need to do is go to the “Management Console → SIP Trunks”, double-click on your BT 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/Number you have to the list in a International Number format (e.g. 448135791691) and press OK once you have finished.
Creating Inbound Rules
Now that you have associated all your DIDs/Number with your SIP Trunk in 3CX, you can create Inbound Rules to set where calls will be routed when those number are called. Instructions on how to create Inbound Rules can be found here.
When configuring BT HSIPT Trunks in 3CX, numbers must be entered in a international format (e.g. 448135791691).
Outbound Caller ID
BT SIP-T Trunks supports only DID numbers to be sent as outbound caller ID.
There are no special instructions regarding Outbound Rules that are required, numbers can be dialed either in national format with the leading 0, or full + e164 format (e.g. +448135791691).