Python alone isn’t quite enough though. For phone calls, SMS and voicemail support you need additional tools, similar to reverse phone lookup for those who are interested in using a caller id system. Enter Twilio.
There is a limit on the VM length but you can modify it. This line of the script has a maxLength parameter, represented in seconds: resp.record(maxLength=”30″, action=”/handle-recording”). If you changed that value from 30 to 120, for example, the max VM recording length would be 120 seconds, for example. Note that the voice mail recording is not stored on the Pi; it’s stored on Twilio’s servers, hence the per minute charge from Twilio for the recording and the service. Is it possible to use it as CCF (conditional call forwarding)? after enabling the forwarding option it should play some pre recorded messages on the basis of who calls ?

8.) Bienvenue sur le Service de John Doe. Malheureusement, toutes les lignes sont occupées pour le moment. Laissez un message après le bip sonore avec votre nom et numéro de téléphone. Nous vous rappellerons dès que possible. Nous vous souhaitons une bonne journée.
A business voicemail greeting or message should be of a high-quality sound recording that sounds very clear and free of any background noise. This can only be achieved if the recording is done in a sound studio with high-quality recording equipment. A professional voice-over artist would either have access to a professional recording studio or own a home recording setup.