# Locations and call admission control

- A CUCM location names a bandwidth budget between sites.
- CAC refuses a call. QoS schedules a call that was allowed.
- Audio and video budgets are separate in current CUCM designs.
- Refused calls show a cause, not silence.
- Locations do not mark DSCP.

If you set the location bandwidth below the real queue, CUCM blocks calls the WAN could have carried. If you set it far above the queue, CUCM admits calls the queue will damage. The two numbers should be designed together.

Site A to site B is 1 Mbit/s for voice in CUCM and 512 kbit/s in the priority queue. The sixth G.711 call is admitted and then sounds broken. Align the location with the queue, or the reverse, on purpose.

## Sources and go deeper

Independent, free, learning-only student project.

Opened 2026-10. A row marked confirm has no link, because that page was not verified.

- Cisco. [System Configuration Guide for CUCM, Release 15](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/15/systemConfig/cucm_b_system-configuration-guide-15.html). last checked 2026-10
- Cisco. [Preferred Architecture for Cisco Collaboration 15, design overview (PDF)](https://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/overview/15x/clbpa15x.pdf). last checked 2026-10
- RFC. [RFC 4594, DiffServ service classes](https://www.rfc-editor.org/rfc/rfc4594). last checked 2026-10
- Cisco. [Cisco Unified Communications Manager product support](https://www.cisco.com/c/en/us/support/unified-communications/unified-communications-manager-callmanager/series.html). last checked 2026-10
- Community. [Cisco Community, Collaboration knowledge base](https://community.cisco.com/t5/collaboration-knowledge-base/tkb-p/4691-docs-collaboration-voice-video). last checked 2026-10
- Wikipedia. [Quality of service (Wikipedia)](https://en.wikipedia.org/wiki/Quality_of_service). last checked 2026-10
- Cisco. Enterprise QoS SRND book. confirm. The Enterprise QoS SRND path returned HTTP 404. last checked 2026-10

Room or sheet file: ../../rooms/sources/locations-cac/sources.json