Cheat code
Firewall cheat sheet
- Phone to CUCM: 69/UDP, 6970/TCP, 5060, 5061, 2000 or 2443, 3804
- Gateway to CUCM: 2427/UDP or 1720/TCP, plus RTP
- RTP between media hosts: UDP 16384–32767 unless you have changed it
- Apps to CUCM: 2748/2749 CTI, 8443 AXL
- CUCM to the world: 123 NTP, 389/636/3268/3269 LDAP, 443 CSSM, 22 backup
- Keep ephemeral 32768–61000 open on the node or phones drop
Source: CUCM 15 TCP and UDP port usage.
Sources and go deeper
Opened 2026-10. A row marked confirm has no link, because that page was not verified.
- Protocol and ports. Cisco Expressway IP port usage (X14.3 and X15.0) last checked 2026-10
- Protocol and ports. CUCM 15 TCP and UDP port usage last checked 2026-10
- RFC. RFC 3550, RTP last checked 2026-10
- RFC. RFC 8445, ICE last checked 2026-10
- Community. Cisco Community, Collaboration knowledge base last checked 2026-10
- Wikipedia. Real-time Transport Protocol (Wikipedia) last checked 2026-10