### Answer The documentation does not mention support for comma-based pause/extension dialing in the

to_number

format (e.g.,

+14371231212,123

) . The Create Phone Call API expects the destination number in E.164 format without extension syntax. [(1) ]() , [(2) ]() Recommended approach: Use the Press Digit tool For dialing extensions or navigating IVR systems on outbound calls, you should use the Press Digit function combined with prompt instructions. [(3) ]() Steps: 1. Add a Press Digit Tool – This gives your agent the ability to press digits during the call. 2. Add Prompt Instructions – Guide your agent on when and what digits to press. For example:

Press digit 1 to reach the support department.

Or if you need to enter an extension immediately:

Press extension 123 after the call connects.

If you're using Conversation Flow, you can use the Press Digit Node, which evaluates whether to press a digit every time the user is done speaking. You can configure a detection delay (recommended 1 second) to ensure the agent doesn't act prematurely. [(4) ]() The Press Digit function automates DTMF (keypad) inputs for seamless IVR navigation. [(5) ]()

​ To learn more, see the sources I considered: [[1] Outbound Calls (Make Calls)](https://docs.retellai.com/deploy/outbound-call) [[2] How can I create an outbound call](https://retell.discourse.group/t/how-can-i-create-an-outbound-call/132) [[3] Press digit (IVR navigation)](https://docs.retellai.com/build/single-multi-prompt/press-digit) [[4] Press Digit Node](https://docs.retellai.com/build/conversation-flow/press-digit-node) [[5] How Can AI Navigate IVRs for Faster Customer Support? | Retell AI](https://www.retellai.com/blog/how-can-ai-navigate-ivrs) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.