Nortel Media Gateway 3200 User Manual page 99

H.248 User's Manual
7.2.3.1 Selecting a Coder or Ptime Using an Under-specified Local
Descriptor
Before the current version, the supported under-specified fields in the SDP had been:
IP address
Port
Payload
Added from the current version, the Profile and Ptime are also supported, as in the
following example:
c=IN IP4 $
m=audio $ $ $
a=ptime:$
The reply is a list of all supported coders.
7.2.3.2 Support of RFC 3407 – Simple Capabilities
RCF 3407 defines a minimal and backward-compatible capability declaration feature in
SDP by defining a set of new SDP attributes. Together, these attributes define a capability
set, which consists of a capability set sequence number followed by one or more capability
descriptions. Each capability description in the set contains information about supported
media formats, but the endpoint is not required to use any of these. In order to actually use
a declared capability, session negotiation must be carried out by the call manager.
Example 1
The following call flows example illustrates the usage of this capability:
MEGACO/1 [10.2.1.228]:2944
Transaction = 10264 {
Context = $ {
v=0
c=IN IP4 $
m=audio $ RTP/AVP 0
m=image $ UDPTL t38
},
v=0
c=IN IP4 10.4.4.46
m=audio 4020 RTP/AVP 0
}}}}}
Version SN09
Add = $ {Media {
LocalControl {
Mode = Receiveonly
},
Local {
Remote {
99
7. Standard Control Protocols
October 2006