Ain't It a Bear? (Q16) |
The information in this article applies to: H.323, H.225.0
There has been recurring confusion over bearer capabilities and in particular the Information-transfer-capability, Transfer-mode, and Information-transfer-rate fields. Here is some pseudocode to show what to set these fields to. I agree that their utility is somewhat questionable, but at least this will show you some sensible values to use. I left multirate out of this logic to make it easier to understand, but a very robust implementation might want to allow the user or administrator to specify this.
if audio-only then Transfer capability = "Speech" Transfer rate = "64 kbit/s" else (audio-and-video) if restricted (to 56kbps ISDN) then Transfer capability = "Restricted digital information" else (unrestricted, e.g., 64kbps ISDN) Transfer capability = "Unrestricted digital information" endif if second called party number (and placed in SETUP.destExtraCallInfo) then Transfer rate = "2 x 64 kbit/s" else Transfer rate = "384 kbit/s" (or, I suppose, "1536 kbit/s" or "1920 kbit/s") endif endif Transfer mode = "Circuit mode" (NEVER "Packet mode"!)