[Freeswitch-users] No dial-tone on Siemens C610

Hi I have deployed 3 cordless Siemens C610 phones on FS and was very surprised that there is no dial-tone when a user makes a call. The users hears a sound similar to an engage signal while FS makes the connection, followed by the sound of the phone ringing once the connection is established. (hope that makes sense). Siemens reckons that is the way their phones behave. Is there a way for FS to simulate a dial-tone while the user waits for the other parties phone to start ringing? Thanks O