Only the higher end Polycoms support Siren7 and Siren14. I believe only the VVX and SoundStation IP phone support those codes.
Asterisk supports G.722.1 (also known as Siren7), and this can be
configured in a config file as either ‘g7221’ or ‘siren7’. Asterisk also
supports G.722.1 Annex C (also known as Siren14), and this can be
configured in a config file as either ‘g7221c’ or ‘siren14’. G.722.1 is
supported only at the 32 kbps bitrate, and G.722.1C is supported only at
the 48 kbps bitrate. Asterisk does not support Siren22.
It’s really hard to guess, since you don’t post any configuration
samples or log captures. In order to debug a problem like this, a ‘sip
debug’ capture showing the SIP signaling and how Asterisk interpreted it
would be required.