When i bought the SPA 921 it came with SIPURA firmware 4.x and i was able to listen the TEL CO'S ring back tone from an ISDN Trunk.
Now i have upgrated the phone to the latest avaliable version 5.1.8 and since then i can not hear the providers ring back tone.
I know about the sticky 183 option but if it set to yes i have no sound at all if it set to no i have only the phone's ring back tone.
With old version if sticky 183 was to yes i had only the provider's tone and if it was to no i had both phone's and provider's tone.
Can anybody help please?