Gradwell - SIP Trunking
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Gradwell is a leading UK SIP Trunk Provider which has the skill, knowledge and technology to provide UK businesses with an affordable and flexible alternative to ISDN, for both in and outbound calls.
Reference website: Gradwell
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 SP1
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 numbers registered under the account can be presented. These can be added on demand if the customer can send proof they own the number
- Catch All Routing: No
- Fax in T38: No, Gradwell provides a separate service for Fax
- Fax in G711: No, Gradwell provides a separate service for Fax
- CLIR (Number Suppression): No
- DTMF via RFC 2833: Yes
- Codec Order: G711A, G711U, G729
- NAT Support: Yes
- Other: Requires Public Static IP, Number blacklist response not handled correctly.
Configuring the Trunk with 3CX
You can access and manage your Gradwell account from here.
Configuring SIP Outbound
To add a SIP Trunk and to enable it to make outbound calls, you need to first access the portal and go to “Billing” → “Packages”, then click “Go”:
In the list of services, scroll to the “SIP Outbound” option and press “Buy now”, then click “continue” on the next page that appears:
You will then come to the following screen where you must whitelist the Static Public IP of your 3CX. You will also see which telephone numbers, if any at the current time, are associated with your account:
Continue the purchase procedure filling in the necessary information requested until the end.
Once SIP Outbound has been added, it can be managed through the portal under the “Setup” → “SIP Outbound”.
Configuring SIP Inbound
Next, you must enable inbound calls while at the same time choosing the telephone numbers you want to associate with your account. To do this you need to go to “Billing” → “Packages”, then click “Go”. Next find the “SIP Inbound” and press “Buy now”:
Proceed with the wizard filling in all necessary information until the end. During this process, at some point you will be asked where you want each telephone number to be forwarded to. We recommend selecting “Please leave my DDIs unconfigured, I will set them up later”. Instructions on how this is done are next.
Once you have purchased the telephone numbers/DIDs you want, you must configure them so that inbound calls to those numbers are correctly routed to your 3CX installation.
To do this go to “Setup” → “SIP Inbound”. Here select all the DIDs/Numbers you want, then in the “Settings” section do the following:
- Set “Platform” to “Custom Settings”
- Check the “SIP number” option and in the drop-down select “E.164 format”
- Check the “SIP server” option and in the text field next to it, type in the Static Public IP of your 3CX
Once you have done the above press the “Apply Settings” button.
Adding the Trunk
The general instructions outlining how to add a new SIP Trunk to your 3CX installation can be found here.
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. You will be asked for the main trunk number which should be in E164 format (e.g. +442033272020). The Main Trunk number can be any of the DIDs you associated with your Trunk as described in section “Configuring SIP Inbound” of this guide.
Once you click the OK button the “General” settings page. Now go to the “Caller ID” tab and here fill in the same number you chose as the Main Trunk number, only this time in the National Format (e.g. 02033272020).
Once you have done this, scroll to the top of the page and click OK.
Adding Additional DIDs
To associate all other DIDs/Numbers you have in your Gradwell account with 3CX, what you need to do is go to the Management Console → SIP Trunks, double-click on your Gradwell 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 E164 Number format (e.g. +442033272020) and press OK once you have finished.
All numbers that belong to the Gradwell trunk must be added as DIDs under the trunk settings.
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
Gradwell trunk supports only DID numbers that are registered under the account to be sent as outbound caller ID. When configuring numbers in 3CX for Outbound Caller ID presentation, the number must be entered in a National format (e.g. 02033272020).
When configuring your Outbound Rules make sure that all numbers are dialed either in the National (e.g. 02033272020) or International format (e.g. 00442033272020). Numbers dialed in any other format (e.g. +442033272020) will be rejected.
More information about how to create Outbound Rules and how they work can be found here.