In Asterisk, dtmf_mode auto sends RFC 4733 if the other side supports it and in-band otherwise; auto_info sends RFC 4733 if supported and SIP INFO otherwise.

Checked 2026-09-24

Vendor
Sangoma
Product
Asterisk res_pjsip
Subsystem
endpoint configuration
Deployment
on-premises
Region
not restricted
Release range
Latest API docs as of 2026-09-24
Checked
2026-09-24

Sources

Cite this note

APA

WarmTransfer. (2026, September 24). DTMF methods and interoperability failures: source note dtmf-interop-asterisk-auto-fallbacks. WarmTransfer. https://warmtransfer.net/knowledge/claims/dtmf-interop-asterisk-auto-fallbacks

BibTeX

@misc{warmtransfer-claim-dtmf-interop-asterisk-auto-fallbacks,
  title  = {DTMF methods and interoperability failures: source note dtmf-interop-asterisk-auto-fallbacks},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/dtmf-interop-asterisk-auto-fallbacks},
  note   = {Source note dtmf-interop-asterisk-auto-fallbacks, checked 2026-09-24}
}

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