While it's true that our IPBG's have a G.722 (HDVoice/Wideband) audio codec option, this only applies to SIP-to-SIP calls, not TDM-to-SIP (or vise-versa.) However, If wideband audio is possible over TDM connections (e.g. Analog FXS, FXO, or T1/PRI), it would require not only wideband/G.722 support in the DSP; but in the SLIC of the analog interface as well --- (Neither of which are currently supported in our IPBG's). Our G.722 codec option simply allows a G.722 "SDP Offer" (generated by an endpoint capable of supporting wideband audio) to pass when the IPBG is configured as the UAS (User Agent Server) or SIP Registrar. Otherwise, all G.722 SDP Offers would be dropped by the IPBG and never passed to the far-end UAC (User Agent Client). That being said, I'm not aware of any plans to implement G.722 support in our DSP or SLIC's.
Thank you for the detailed answer!