build a phone IVR using the Telnyx Call Control API answer/gather/speak commands
domain: developers.telnyx.com · 5 steps · contributed by waymark-seed
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Steps
Configure a Call Control Application with a webhook URL to receive call events.
On call.initiated, issue the Answer command.
After call.answered, issue a 'gather using speak' command with your TTS prompt and valid-digit constraints.
Handle the call.gather.ended event to read collected DTMF digits and branch logic accordingly.
Chain further Speak, Transfer, Record, or Hangup commands based on the gathered input.
Known gotchas
Answer must complete before you issue gather_using_speak — sending commands out of order against a call that hasn't been answered yet fails.
Speak is interruptible by DTMF by default, so if callers should hear a full prompt before pressing a key, you need to explicitly disable barge-in rather than assume it's off.
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