3CX SIP Trunk Providers - USA
The SIP Trunk Providers listed for the USA have demonstrated compatibility with the 3CX Phone System. They are categorized as either 3CX Tested, where testing is completed directly by 3CX, or VoIP Provider Tested, where the provider completes the required testing and submits the results to 3CX for review. We recommend choosing a listed provider and checking its interoperability category, capabilities and configuration notes before setup.
For hosted installations, registration-based trunks that do not require a fixed IP are preferred. In certain cases, the public IP address of a Hosted by 3CX system may change. Although uncommon, this can temporarily affect incoming and outgoing calls when using an IP-based trunk.
Read our guide on how to configure a SIP Trunk / VoIP Provider. It explains the general steps for configuring a trunk with 3CX. Some providers have additional requirements, so check the provider’s listing and follow any configuration notes or guides provided.
3CX Tested
These providers have been tested directly by 3CX and meet the applicable technical, support and commercial requirements. Their pre-configured templates are available in 3CX for quick and easy setup.
Capabilities
| SMS Support | No |
| Anonymous Calling | No |
| Clip No Screening Support | No |
| Fax Support | Yes - T38 Bypass |
| SIP TLS Support | No |
| IPV6 Ready | No |
| Online Sign-Up & Portal | Yes |
Important Configuration Notes
Enter the main trunk number in international format (e.g. 17778811960).
You can only present numbers associated with your account as Outbound Caller ID.
Be sure to follow the configuration guide.
Capabilities
| SMS Support | No |
| Anonymous Calling | Yes |
| Clip No Screening Support | Yes |
| Fax Support | Yes - T38 Upscale |
| SIP TLS Support | No |
| IPV6 Ready | Yes |
| Online Sign-Up & Portal | Yes |
Important Configuration Notes
Enter the main trunk number in the national format (e.g. 7778811960).
CenturyLink supports SRTP. Enable it from the trunk settings in the Management Console "Options > Advanced > SRTP Mode".
Capabilities
| SMS Support | Yes |
| Anonymous Calling | No |
| Clip No Screening Support | Yes |
| Fax Support | Yes - T38 Bypass |
| SIP TLS Support | Yes |
| IPV6 Ready | No |
| Online Sign-Up & Portal | Yes |
Important Configuration Notes
Enter the main trunk number as E164.
Be sure to follow the configuration guide.
Capabilities
| SMS Support | No |
| Anonymous Calling | Yes |
| Clip No Screening Support | Yes |
| Fax Support | No |
| SIP TLS Support | No |
| IPV6 Ready | No |
| Online Sign-Up & Portal | Yes/Yes |
Important Configuration Notes
Enter the main trunk number as E164.
Capabilities
| SMS Support | No |
| Anonymous Calling | Yes |
| Clip No Screening Support | Yes |
| Fax Support | No |
| SIP TLS Support | No |
| IPV6 Ready | No |
| Online Sign-Up & Portal | No/Yes |
Important Configuration Notes
(for resellers only)
Enter the main trunk number in international number format (e.g. 17778811960).
Capabilities
| SMS Support | Yes |
| Anonymous Calling | Yes |
| Clip No Screening Support | No |
| Fax Support | No |
| SIP TLS Support | No |
| IPV6 Ready | No |
| Online Sign-Up & Portal | Yes |
Important Configuration Notes
Enter the main trunk number as E164.
Be sure to follow the configuration guide.
VoIP Provider Tested
These providers have completed the required 3CX interoperability testing and submitted their results for review. Once approved, their pre-configured templates are made available in 3CX. This category does not mean that 3CX has directly tested the provider’s overall service.
Capabilities
| SMS Support | No |
| Anonymous Calling | Yes |
| Clip No Screening Support | Yes |
| Fax Support | No |
| SIP TLS Support | No |
| IPV6 Ready | No |
| Online Sign-Up & Portal | No/Yes |
Important Configuration Notes
Enter the main trunk number as E164.
Capabilities
| SMS Support | Yes |
| Anonymous Calling | Yes |
| Clip No Screening Support | Yes |
| Fax Support | Yes - T38 Bypass |
| SIP TLS Support | No |
| IPV6 Ready | No |
| Online Sign-Up & Portal | Yes |
Important Configuration Notes
Enter the main trunk number as E164.
Be sure to follow the configuration guide.
Capabilities
| SMS Support | No |
| Anonymous Calling | Yes |
| Clip No Screening Support | Yes |
| Fax Support | No |
| SIP TLS Support | No |
| IPV6 Ready | No |
| Online Sign-Up & Portal | No |
Important Configuration Notes
Enter the main trunk number in the national format (e.g. 7778811960).
Under the “General” tab, enter the primary SIP Server IP.
Under the “Options” tab in the “Alternative Proxy” field add the secondary IP.
To use “Clip No Screening” request the functionality from Convergia.
By default, only numbers associated with your account can be presented as outbound caller ID.
A static public IP is required.
Capabilities
| SMS Support | Yes |
| Anonymous Calling | Yes |
| Clip No Screening Support | Yes |
| Fax Support | No |
| SIP TLS Support | No |
| IPV6 Ready | No |
| Online Sign-Up & Portal | Yes |
Important Configuration Notes
Enter the main trunk number as E164.
Dialling must be in either 11 digit format (17778811960)0 or full +E164 format (+17778811960).
Be sure to follow the configuration guide.
Capabilities
| SMS Support | Yes |
| Anonymous Calling | Yes |
| Clip No Screening Support | Yes |
| Fax Support | Yes - T38 Bypass |
| SIP TLS Support | No |
| IPV6 Ready | No |
| Online Sign-Up & Portal | No |
Important Configuration Notes
Enter the main trunk number as E164.
Capabilities
| SMS Support | No |
| Anonymous Calling | Yes |
| Clip No Screening Support | Yes |
| Fax Support | No |
| SIP TLS Support | No |
| IPV6 Ready | No |
| Online Sign-Up & Portal | No/Yes |
Important Configuration Notes
Enter the main trunk number as E164.
Capabilities
| SMS Support | No |
| Anonymous Calling | Yes |
| Clip No Screening Support | Yes |
| Fax Support | No |
| SIP TLS Support | No |
| IPV6 Ready | No |
| Online Sign-Up & Portal | No/Yes |
Important Configuration Notes
Enter the main trunk number in international number format (e.g. 17778811960).
For calls within the US, you must enter the number in the 11 digit format.
For international calls enter only the country code without the "+" and without 011.
Be sure to follow the configuration guide.
Capabilities
| SMS Support | Yes |
| Anonymous Calling | Yes |
| Clip No Screening Support | Yes |
| Fax Support | Yes - T38 Bypass |
| SIP TLS Support | No |
| IPV6 Ready | No |
| Online Sign-Up & Portal | Yes |
Important Configuration Notes
Enter the main trunk number as E164.
Be sure to follow the configuration guide.
Capabilities
| SMS Support | No |
| Anonymous Calling | Yes |
| Clip No Screening Support | No |
| Fax Support | No |
| SIP TLS Support | No |
| IPV6 Ready | No |
| Online Sign-Up & Portal | Yes |
Important Configuration Notes
Enter the main trunk number as E164.
Outbound rules: numbers must be dialed only in E164 format. Disable the "E164 Processing" from the MC > Settings.
Capabilities
| SMS Support | Yes |
| Anonymous Calling | Yes |
| Clip No Screening Support | Yes |
| Fax Support | Yes - T38 Bypass |
| SIP TLS Support | Yes |
| IPV6 Ready | No |
| Online Sign-Up & Portal | Yes |
Important Configuration Notes
Enter the main trunk number as E164.
Capabilities
| SMS Support | Yes |
| Anonymous Calling | No |
| Clip No Screening Support | No |
| Fax Support | Yes - T38 Bypass |
| SIP TLS Support | No |
| IPV6 Ready | No |
| Online Sign-Up & Portal | Yes |
Important Configuration Notes
Enter the main trunk number in national format (e.g. 7778811960).
Be sure to follow the configuration guide.
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