Under RFC 3398, when an early ACM (called party status no indication) is received, the gateway SHOULD send 183 Session Progress toward SIP.

Checked 2026-09-24

Vendor
IETF
Product
SIP-ISUP gateways
Subsystem
call progress mapping
Deployment
carrier, on-premises
Region
not restricted
Release range
current as of 2026-09-24
Checked
2026-09-24

Sources

Cite this note

APA

WarmTransfer. (2026, September 24). SS7 and carrier interworking concepts: source note ss7-carrier-interworking-early-acm-183. WarmTransfer. https://warmtransfer.net/knowledge/claims/ss7-carrier-interworking-early-acm-183

BibTeX

@misc{warmtransfer-claim-ss7-carrier-interworking-early-acm-183,
  title  = {SS7 and carrier interworking concepts: source note ss7-carrier-interworking-early-acm-183},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/ss7-carrier-interworking-early-acm-183},
  note   = {Source note ss7-carrier-interworking-early-acm-183, checked 2026-09-24}
}

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