The 8.6 SME guide notes that IP PSTN service providers typically require SIP Early Offer on trunks to them and that most support voice calls only.

Checked 2026-09-25

For SIP trunks to an IP PSTN, SIP Early Offer is typically required by the service provider, and most providers support voice calls only.
Vendor
Cisco
Product
Unified Communications Manager Session Management Edition
Subsystem
PSTN access
Deployment
on-premises
Region
not restricted
Release range
Unified CM 8.5-8.6
Checked
2026-09-25

Sources

Cite this note

APA

WarmTransfer. (2026, September 25). Unified CM Session Management Edition: source note cucm-session-management-edition-ip-pstn-early-offer. WarmTransfer. https://warmtransfer.net/knowledge/claims/cucm-session-management-edition-ip-pstn-early-offer

BibTeX

@misc{warmtransfer-claim-cucm-session-management-edition-ip-pstn-early-offer,
  title  = {Unified CM Session Management Edition: source note cucm-session-management-edition-ip-pstn-early-offer},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/cucm-session-management-edition-ip-pstn-early-offer},
  note   = {Source note cucm-session-management-edition-ip-pstn-early-offer, checked 2026-09-25}
}

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