[cisco-voip] CCM Trace Question || MediaManager & PTime

Daniel Pagan dpagan at fidelus.com
Tue Jul 15 10:28:35 EDT 2014


Folks:

Quick question on the preCheckCapabilities step for MediaManager. After a new MediaManager is created, I've often referred to the preCheckCapabilities line for determining codec and DTMF relay capabilities based on codec type numbers (Cap,ptime) and figured that ptime was simply the payload size in ms. While looking at a recent issue, I noticed that ptime didn't exactly match up with packet time values specified in CCM service parameter settings. The environment was using default settings across the board for packet size in milliseconds, but advertised capabilities shown in preCheckCapabilities for an IP phone to IP phone call showed:

(Cap,ptime)= (25,40) (4,40) (2,40) (15,60) (16,60) (11,60) (12,60)

Here I'm seeing g.711 with a ptime value of 40 and g.729 with 60. In this environment, g.711 and g.729 is configured for 20 ms packet size. So for clarification, assuming my understanding is incorrect, can someone tell me what the ptime value represents? We also thought maybe maximum payload size in ms but service these values go beyond the allowable values in CUCM.

Thanks ahead of time!

- Daniel


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