The XSF has issued a Last Call on XEP-0262, which describes implementation considerations related to audio codecs for use in Jingle RTP sessions, and recommends PCMU and PCMA (G.711) as mandatory-to-implement technologies to provide a baseline for interoperability.
If you have feedback, please post to the jingle@xmpp.org or standards@xmpp.org discussion list before July 8, 2011.