SIP REFER for All Call Transfers | Telnyx Release Notes

We’re excited to announce that Telnyx Voice API users can now transfer calls using the SIP Refer method. SIP Refer enables greater control over your communications by providing a reliable means of transferring calls between parties within your organization, or to the PSTN.

Sending a REFER message via Call Control programmable voice API

Customers can request that a call be transferred by using Call Control, our programmable voice API. Refer commands can be sent from a Call Control application at any time during a call. This will initiate a transfer of one of the parties from the initial Telnyx call onto a new call to an external destination, without Telnyx in the call path.

This transfer method can also be used to establish a new call between the two parties from the initial Telnyx call, without Telnyx in the call path. This use-case is especially useful for calls on which sensitive information is disclosed - by removing itself from the call path, Telnyx adds an extra layer of protection to these calls.

Initiating a transfer on any Telnyx call using the Refer command adds a $0.10 surcharge to the cost of the call.

Include context with transferred calls via SIP UUI header

Context can be passed along with transferred calls in the form of SIP UUI headers. For example, a support agent who collects information from a customer can attach this information in SIP UUI headers when transferring the call to another support agent, ensuring the customer only needs to provide their information once.

For more information on transferring calls using SIP REFER, check out our docs. Note that this new functionality is not supported in V1 of our API. Learn more about migrating to the new Telnyx API V2.

Curious about using SIP REFER to build greater functionality into your comms? Talk to our SIP experts to learn more.