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About C2 Communications
C2 Communications is based in Melbourne and, with over 10 years of experience in helping businesses with their telephony needs, is one of the leading VoIP providers in Australia. C2 Communications’ SIP Trunking service enables businesses to save up to 50% on their telco bills and is now available from within the 3CX management console.
Reference website: C2 Communications
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 v15.5
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
- Fax T.38 support: Yes
- CLIR (Number Suppression): Yes
- DTMF via RFC 2833: Yes
- Codec Order: G711U, 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: AU
- Select Provider in your Country: C2 Communications
- Main trunk number: This will have been provided to you by C2 Communications. You must enter the number in the international number format (e.g. 0285203570)
- Press OK
Under the “General” tab in the “Authentication” section enter your:
- Authentication ID - This will usually be your main trunk number in the national number format
- 3-Way Authentication Password
(these will be supplied to you by C2 Communications)
Once you have filled in these fields as given to you by C2 Communications, scroll to the top of the page and press OK. At this point if you refresh the page you should see your C2 Communications Trunk appear as Registered.
Adding Additional DIDs
To associate all other DIDs/Numbers you have in your C2 Communications account with 3CX, go to the Management Console → SIP Trunks, double-click on your C2 Communications Trunk and go to the “DIDs” tab.
Here you should already see 1 entry, that is the Main Trunk number you have set which should be in the national number format (e.g. 028520357). This should remain as is.
All other DIDs should also be added to the list, but not in the same number format. All other number should be added be keeping the last 8 digits and place a * in front. So if your DID number is 028520357, you would add it as *28520357.
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.
Outbound Caller ID
C2 Communications Trunks does not support Clip No Screening which means you can only present numbers as Outbound Caller ID that are assigned to your trunk. These numbers must be presented in a national format (e.g. 0285203570).
For Outbound Calls, any valid dialable number format can be user. More information about how to create Outbound Rules and how they work can be found here.
Upon testing it was observed that when a call is rejected by the phone system, C2 Communications will send a second invite to make sure the rejection was rejected intentionally.