ZyXEL Communications MSC1000G - Voice Coding

Chapter 16 VoIP
Management Switch Card User’s Guide
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16.1.4.4 H.248 and the IES
Configure each of the IES’s H.248 interfaces to associate with a media gateway controller in order
to let subscribers make calls through the VOP MC cards.
• You can configure each of the IES’s VOP1248G-61 or VOP1372G-61 cards as an SC or an MC in
the VoIP > VoIP H248 screen.
• Each IES H.248 interface requires specific information about a media gateway controller with
which it is to associate. This information is specified in an H.248 profile. Configure H.248 profiles
in the Profile > VoIP H248 screen.
• Configure the IES’s H.248 interfaces in the VoIP > VoIP Interface screen. You must specify the
SCs, MCs, H.248 profile, MG details and other settings for the IES H.248 interface.
•Use the Port > VoIP H248 screen to manage and configure other VoIP settings of each port on
your H.248 line card(s).
16.1.5 RTP
When you make a VoIP call using SIP or H.248, the RTP (Real time Transport Protocol) is used to
handle voice data transfer. See RFC 1889 for details on RTP.
16.1.6 Voice Coding
A codec (coder/decoder) codes analog voice signals into digital signals and decodes the digital
signals back into voice signals. The VOP supports the following codecs.
MGC --> MG1 MGC modifies analog Termination on MG1 to stop playing ringing tone
to phone A.
Modify
MGC --> MG2 MGC modifies analog Termination on MG2 to stop ringing phone B. Modify
MGC --> MG1 MGC modifies RTP Termination on MG1 to transfer media with RTP
Termination on MG2.
Modify
MGC --> MG2 MGC modifies RTP Termination on MG2 to transfer media with RTP
Termination on MG1.
Modify
Phone A --> MG1 User of phone A finishes call and replaces receiver on hook. N/A
MG1 --> MGC MG1 reports on-hook to MGC. Notify
MGC --> MG1 MGC removes MG1’s RTP Termination from its Context. The RTP
Termination is ephemeral and is destroyed.
Subtract
MGC --> MG1 MGC removes phone A’s analog Termination from its Context. The
Context is destroyed. The analog Termination is physical and returns to
the Null Context.
Subtract
MGC --> MG2 MGC removes MG2’s RTP Termination from its Context. The RTP
Termination is ephemeral and is destroyed.
Subtract
MGC --> MG2 MGC removes phone B’s analog Termination from its Context. The
Context is destroyed. The analog Termination is physical and returns to
the Null Context.
Subtract
Table 327 H.248/MEGACO Call Procedure Example
DIRECTION ACTION COMMAND