AltiGen MAXCS 7.5 New Features Guide - Manual (Page 12)

MaxCS 7.5 New Features Guide Page 12 of 22
Codec Negotiation
The logic for negotiating codec capabilities varies for various types of connection.
Codec Negotiation – Server to Client
With a server-to-client connection, the highest priority codec in the server’s codec list that is supported by the
client will be assigned.
Following is an example of a typical setting for SIP devices on a LAN: G.722, then G.711 Mu-Law. This hierarchy
allows Polycom phones and the AltiGen IP-805 phone to connect via G.722. AltiGen IP phones will connect with
G.711.
The next example shows a typical setting for SIP devices on a WAN: First G.729, the G.723.1, and then G.711 u-
Law. This hierarchy allows remote SIP devices to use the compressed codec G.729. Remote IPTalk instances use
G.723.1, and G.711 is used for other remote devices that do not support the other two codecs.
Codec Negotiation – Server to Server
With server-to-server connections, the responding device determines the codec from the common codecs that
both of the devices accept. Usually, the responding device selects the first preferred codec from among the
common list. We recommend that you assign a preferred codec on both servers, so that both incoming and
outgoing events use the same codec.
If you are not sure of the codecs supported by your SIP Trunk provider, then we recommend that you configure a
single codec (your preferred codec) for SIP Trunks.