Configuring Singtel SIP Trunk in 3CX
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The Singtel Group is Asia's leading communications group, with their headquarters in Singapore. They provide a diverse range of services including fixed, mobile, data, internet, TV, infocomms technology (ICT) and digital solutions.
Reference Web Address: SingTel
In order to use a SingTel SIP Trunk with 3CX, the 3CX Server needs to have a second network card which will only be used for traffic from and to the SingTel servers. The network topology should look similar to the following:
NIC 1 should connected to the main LAN through which the 3CX Server will have access to the internet and will also be the LAN on which Extensions are connected to.
NIC 2 will only cater for traffic from/to the SingTel servers.
3CX Server NIC Setup
For NIC 1, apply the necessary network settings required by your network.
For NIC 2, you must manually configure the SingTel WAN IP address that has be given to you and as per the instruction by SingTel, e.g.:
Important! NIC 2 must not have a Default Gateway configured and the DNS servers must be blank.
Adding Static Routes
Next you must add a static route so that the traffic from the 3CX server towards the SingTel servers is routed out through the correct Gateway. To do this on a Windows OS, you would open a command prompt using the “Run as Administrator” option, then run the following command:
route -p add 220.127.116.11 mask 255.255.255.0 METRIC 1 [Gateway IP given by Provider]
route -p add 18.104.22.168 mask 255.255.255.0 METRIC 1 22.214.171.124
The Gateway IP that you need to configure should be given to you by SingTel.
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
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, static SI per trunk
- Fax in T38: No
- CLIR (Number Suppression): No
- DTMF via RFC 2833: Yes
- Codec Order: G729, G711U, G711A
- NAT Support: Yes
- Other: SRTP is not supported, TLS is not supported
Collecting 3CX Configuration Settings
In order to configure SingTel with 3CX, you should first make sure you have the following information available which must be provided to you by your SingTel representative:
- Your DID numbers
- The SingTel SIP Server IP address
- Your SingTel WAN IP Address (also used in section 3CX Server NIC Setup)
With the above information you can proceed to the next section which explains how you use this information to configure the Trunk in 3CX.
Configuring the Trunk with 3CX
Adding the Trunk
The general instructions outlining how to add a new SIP Trunk to your 3CX installation can be found here.
Additionally, for SingTel, you must also have a dedicated NIC for the traffic from/to the Provider. The instruction for this are provided in section “System Preparation” and must be done prior to the following.
To add SingTel to your 3CX system, open the Management Console and navigate to “SIP Trunks”. Press the “Add SIP Trunk” button and select “SG” as the country and then “SingTel” from the following drop-down.
In the “Main Trunk No” field, enter one of your DID numbers, then press OK.
Once you have done this, in the “General” tab fill in the SingTel SIP Server IP given to you by the Provider in the “Registrar” field:
Next, go to the “Options” tab and in the “Advanced” section, fill in the SingTel WAN IP you have been given.
Once you have done the above, press OK and your Trunk will now be configured.
Adding Additional DIDs
To associate all other DIDs/Numbers you have on your SingTel Trunk, what you need to do is go to the Management Console → SIP Trunks, double-click on your SingTel 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 National Number format.
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.
Outbound Caller ID
When making Outbound Calls using your SingTel SIP Trunk, can present any of your DIDs as the Outbound Caller ID. Note though that because Clip No Screening is not supported, you cannot present any other number that you don’t have associated to your Trunk.
There are no special instructions regarding Outbound Rules that are required, numbers can be dialed either in any valid format.
More information about how to create Outbound Rules and how they work can be found here.