Source note · SIP trunk carrier turn-up and acceptance testing
RFC 4733 says DTMF digits 0-9, * and # are commonly supported and that digits A through D are less frequently encountered.
Checked 2026-09-25
DTMF digits A through D are less frequently encountered
- Vendor
- IETF
- Product
- RTP telephone-event payload
- Subsystem
- dtmf
- Deployment
- any
- Region
- not restricted
- Release range
- RFC 4733
- Checked
- 2026-09-25
Sources
- RFC 4733: RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals — IETF / RFC Editor · tier 1 standards and regulators · Section 3.2
Cite this note
APA
WarmTransfer. (2026, September 25). SIP trunk carrier turn-up and acceptance testing: source note sip-trunk-carrier-turn-up-rfc4733-a-d-less-common. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-trunk-carrier-turn-up-rfc4733-a-d-less-common
BibTeX
@misc{warmtransfer-claim-sip-trunk-carrier-turn-up-rfc4733-a-d-less-common,
title = {SIP trunk carrier turn-up and acceptance testing: source note sip-trunk-carrier-turn-up-rfc4733-a-d-less-common},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-trunk-carrier-turn-up-rfc4733-a-d-less-common},
note = {Source note sip-trunk-carrier-turn-up-rfc4733-a-d-less-common, checked 2026-09-25}
}