300-070 · Question #412
Which codec is advertised through the SIP trunk if these settings are applied in Cisco Unified Communications Manager?
The correct answer is B. G.729. The codec advertised on a Cisco UCM SIP trunk is controlled by region settings, and the applied configuration restricts the trunk to G.729 only.
Question
Which codec is advertised through the SIP trunk if these settings are applied in Cisco Unified Communications Manager?
Exhibit
Options
- AG.722
- BG.729
- CG.711 and G.722
- Dall codecs supported by the phone
How the community answered
(37 responses)- A3% (1)
- B78% (29)
- C14% (5)
- D5% (2)
Why each option
The codec advertised on a Cisco UCM SIP trunk is controlled by region settings, and the applied configuration restricts the trunk to G.729 only.
G.722 is a wideband 64 kbps codec and would only be advertised if the region explicitly permitted wideband audio.
G.729 is advertised because the region assigned to the SIP trunk restricts the maximum audio bit rate to 8 kbps, which maps exclusively to G.729. UCM uses region settings to build the SDP offer sent across the SIP trunk, so a region capped at 8 kbps includes only G.729 in the codec list.
Both G.711 and G.722 together would only appear if the region allowed higher-bandwidth codecs alongside narrowband options.
Advertising all phone-supported codecs would occur only if the region is unrestricted and the SIP profile permits the full device capability list.
Concept tested: Cisco UCM SIP trunk codec advertisement via region bandwidth settings
Source: https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/12_5_1/systemConfig/cucm_b_system-configuration-guide-1251/cucm_b_system-configuration-guide-1251_chapter_01001.html
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