Delay to call a number with extension

Support Help
1

I’m performing a call transfer to a number with an extension. The process uses Agentic Warm Transfer to move the call to another live agent who will handle the interaction, but the delay in this step is noticeable when the call is made to the PBX.

My questions are:

  • Is there any way to optimize latency or reduce the wait time in the transfer process with Agentic Warm Transfer?
  • Are there any specific settings in the Two-way Conversation Agent that might be causing this delay?
  • What recommendations do you have for improving the efficiency of call transfers with extensions?

Thank you in advance for your help.

2

Hi @web

To reduce wait times during transfers, you can try the following optimizations:

  • Transfer Dial Timeout: Lower the dial timeout in the Call Transfer Node to avoid long ringing durations.

  • Agent Answer Wait Time: Reduce the wait time in Agentic Warm Transfer settings so the system doesn’t wait too long for a bridge/cancel decision.

For two-way conversation agents, keep in mind that the transfer agent interacts with the target before bridging. Using a faster LLM model for this node can significantly reduce latency. You can also enable “Speak During Execution” to keep the caller engaged while the transfer is in progress.

If you’re dialing extensions, note that IVR navigation can add delays. Using the “Navigate IVR” prompt can help the agent move through the system more efficiently.

Finally, for overall latency improvements, we recommend using faster models and low-latency voice providers to optimize end-to-end performance.

Best regards

3

Thank you very much for the information.

And I’d like to know what type of call is best for a PBX by extension?

With the Static Destination option, is it better to handle the SIP extension URI or a static phone number with the extension?

Can it be handled in a static transfer using a dynamic variable?

4

Hi @web

For PBX by extension, you can use the Transfer Call tool with a warm transfer — this is ideal because it supports Navigate IVR, which lets you provide a prompt to help the agent navigate an IVR/PBX system to reach the correct extension.

Static destination options: You can use either:

  • A phone number in E.164 format with the extension field (supports digits 0-9, *, #, e.g. 123#), or

  • A SIP URI (sip:username@domain)*

Both work. The extension field is specifically designed for this use case.

Dynamic variables: Yes! The transfer destination supports a dynamic variable that gets substituted at runtime, so you can dynamically set the transfer number (and extension) without hardcoding it.

For more details, you can see the ( Transfer call - Retell AI ) page.

Thank You