Configuring a VoIP Provider / SIP Trunk
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VoIP providers “host” phone lines and replace the traditional telco lines. VoIP providers can assign local numbers in one or more cities or countries and route these to your phone system. In most cases they also support number porting.
VoIP providers are often able to offer better call rates because they may have an international network or have negotiated better rates. Therefore, using VoIP providers can reduce call costs. However, be aware that each VoIP call requires bandwidth. VoIP is real time, so it does place a demand on your Internet connection. As a rule of thumb, each call will consume approximately 30-120 kb per second, depending on which codec you use. The document, Bandwidth Overhead over DSL connections, includes detailed information about bandwidth consumption, including particular codecs bandwidth usage.
3CX recommends using supported VoIP providers. All supported VoIP providers have been tested for interoperability with 3CX Phone System, and are re-tested with each new build. Their configuration templates are also included with 3CX Phone System to allow you to quickly and easily add them. See the list of 3CX Supported SIP Trunk Providers.
3CX Phone System supports two types of VoIP providers:
- Registration Based – These VoIP providers require the PBX to register with the provider using an authentication ID and password. Most of the VoIP providers pre-defined in 3CX Phone System are registration based.
- IP Based / SIP Trunk – IP Based VoIP Providers (also known as SIP Trunks) do not generally require the PBX to register with the provider. The IP address of the PBX needs to be configured with the provider, so that it knows where calls to your number should be routed.
Requirements for using a VoIP Provider / SIP Trunk
If you plan to use a VoIP provider, you need to have a firewall/router/NAT device that supports STATIC PORT MAPPINGS. Often routers will perform port address translation, which will cause problems such as one way audio, failing inbound calls and so on. It is also highly recommended that you have an FQDN that resolves to a static external IP. If your external IP changes intermittently, inbound calls will fail. See the Firewall & Router Configuration for details to configure your firewall/router/NAT device.
Configuring a VoIP Provider / SIP Trunk
Step 1: Create an Account with a VoIP Provider
First, you need to have an account with a VoIP service provider. 3CX Phone System supports most popular SIP based VoIP service providers and we recommend using one that has been tested by 3CX as 3CX includes pre-configured templates for these VoIP providers. Go to https://www.3cx.com/partners/voip-providers/ to see a list of supported providers.
Step 2: Add the VoIP Provider Account in 3CX Phone System
After you have created the VoIP provider account, you will need to configure the account in 3CX Phone System. To do this:
- In the 3CX Phone Management Console menu, select “SIP Trunks” > “Add Provider”
- 3CX Phone System will prompt you to conduct a Firewall Test. Frequently, the internet facing firewall sitting between 3CX Phone System and the VoIP provider is not correctly configured or is not able to correctly route VoIP traffic. To check the firewall configuration, it is important to perform a firewall check using the inbuilt firewall checker.
- Click “Run Firewall Checker”.
- Ensure that the tests for the SIP Port (default port 5060), and the Audio Port range (default ports 9000-9255) all pass with success. If the firewall check fails, you must go to your firewall and troubleshoot why the test failed.
- After successfully completing the test, return to the VoIP Provider Wizard.
Note: 3CX does not provide specific firewall configuration support.
- Enter a friendly name for this VoIP provider account.
- Select the Country that the VoIP provider operates in.
- Select your VoIP provider from the Provider drop down list. If the provider is not listed, select “Generic VoIP Provider”, or “Generic SIP Trunk”, (If using a generic provider we will not be able to guarantee that 3CX will work with this VoIP provider), Click “Next”.
- The SIP server hostname or IP may be pre-filled. Compare these with the details that you have received from your VoIP provider and check that these are indeed correct. Depending on the VoIP provider that you are using, some fields will be disabled. This means you do not need to change them. Click “Next” to continue.
- Now enter the VoIP provider account details. In the External number field, enter the VoIP line number that has been assigned to you. Then enter the Authentication ID/username and password of your VoIP provider account. Specify the number of simultaneous calls your provider allows. Click “Next” to continue. If you are using a SIP trunk, the password will be greyed out, since authentication is done via IP.
- Specify how calls from this VoIP provider should be routed. You can specify a different route outside office hours. The routing configured here will take effect when no inbound routing rules are matched.
- On the next page, you can optionally configure an outbound call rule, which will be used to route outbound calls through the new provider. This is normally done by routing calls starting with a specific prefix. Enter the dialling prefix in the “Calls to numbers starting with (prefix)” text box. To make calls via this provider, precede the number to be dialled with this prefix.
More about Outbound and Inbound Rules can be found in the Trunk Management Section.
DID’s and Inbound Call Identification
If your VoIP provider has provided you with DID numbers, you will need to specify these in the DID tab. To do this:
- In the 3CX Management Console, select “SIP Trunks” click on the VoIP provider you want to configure.
- Click on the “DID” tab.
- Add the DID numbers associated with your account. An Inbound Rule, which can be configured at a later stage, will be created for each number specified in this list.
You can also see the list of inbound rules by expanding the “Inbound Rules” node.
More about Inbound Rules can be found in Chapter 8.
- See the Firewall & Router Configuration to configure your firewall/router/NAT device.
- Find more about Outbound and Inbound Rules in the Trunk Management Section.
- Add How much dedicated bandwidth do I need for VoIP? See the Bandwidth Overhead over DSL connections guide to find out.
- See the list of 3CX Supported SIP Trunk Providers.