Cisco's example public DNS for H.323 publishes _h323cs._tcp on port 1720 for call signalling, plus _h323ls._udp and _h323rs._udp on port 1719, all targeting the Expressway-E.

Checked 2026-09-25

Vendor
Cisco
Product
Cisco Expressway
Subsystem
DNS
Deployment
on-premises
Region
not restricted
Release range
X14.0 guide
Checked
2026-09-25

Sources

Cite this note

APA

WarmTransfer. (2026, September 25). Expressway business-to-business calling: source note expressway-b2b-calling-public-h323-srv-set. WarmTransfer. https://warmtransfer.net/knowledge/claims/expressway-b2b-calling-public-h323-srv-set

BibTeX

@misc{warmtransfer-claim-expressway-b2b-calling-public-h323-srv-set,
  title  = {Expressway business-to-business calling: source note expressway-b2b-calling-public-h323-srv-set},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/expressway-b2b-calling-public-h323-srv-set},
  note   = {Source note expressway-b2b-calling-public-h323-srv-set, checked 2026-09-25}
}

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