Patch AMD vs carrier AMD
Twilio and Telnyx both offer answering machine detection on their own calls. Here is how a detector that understands what is said differs, and when each makes sense.
| Feature | Patch AMD | Carrier AMD (typical) |
|---|---|---|
| How it decides | Understands what is said, in real time | Audio cues: greeting length, silence, beep |
| Works with | Twilio, Telnyx, or any raw audio stream | That carrier only |
| Distinguishes voicemail, phone menu and dead number | Varies by carrier and mode | |
| Explains its decision | Reason code plus the words it heard | Result only |
| Public benchmark | OpenAMD English subset, method published | Not published |
| Failure mode | Fails open (not_sure), not charged | Varies |
| Stores audio or transcripts | No | Per carrier policy |
| Price per answered call | $0.007, down to $0.004 at volume; 250 free a month | Telnyx premium $0.0065 · Twilio $0.0075 |
Why words beat timing
Classic AMD measures how long the greeting is and listens for a beep. A person who answers “Hi, this is Sandy, how can I help you?” talks for as long as a short voicemail, and “Hello? … Hello?” has the same rhythm as a recording. Patch AMD understands what is said and applies a conservative decision policy: it connects a person once they are waiting for a reply, and hangs up as soon as the words could only come from a recording.
When carrier AMD is enough
If you only dial on one carrier, can tolerate a few seconds of dead air, and mostly need to know whether to leave a voicemail after the beep, built-in AMD is simple and already integrated. Patch AMD is for teams that connect live reps or AI agents and want both fewer recordings connected and fewer people hung up on, on any carrier.
What we have not measured
We have not run Twilio AMD or Telnyx premium detection on the same benchmark, so this page makes no accuracy claim about them. Our own results are on the benchmark page. Prices are the carriers’ public list prices per call as of November 2026.