T46G 28.80.0.70 ring back issues

Hi all!!!!!

We have just updated some of our T46G models from version 28.72.0.49 to 28.80.0.70 maintening all the configuration parameters, and now we have lost the ring back tone when an internal call is made.

Also we have detected that when an internal call is not answered, as the caller hungs up the phone, the called phone remains ringing.

Do you know how to deal with this?? At the moment we have downgraded again the phones to 28.72.0.49

Thanks