asterisk users - Feb 2005 - Polycom 300 -- "No compatible codecs!"

I've got all three CODECs the 300 supports -- G.711u, G.177A, and 
G.729AB -- enabled, I've changed the order, I've got them all in allow 
lines in my sip.conf, as follows:

disallow=all
allow=ulaw
allow=alaw
allow=G729

 From "sip debug" I get the following snippets:
==================================================================================Found
description format G729
Found description format PCMA
Found description format PCMU
[...]
Non-codec capabilities: us - 0x1 (g723), peer - 0x1 (g723), combined - 
0x1 (g723)
Feb 11 20:05:51 NOTICE[8718]: chan_sip.c:2789 process_sdp: No compatible 
codecs!
==================================================================================
Any ideas where I'm going awry?

Thanks,

-Ken