If you call out and reach a voicemail, you may find in some cases that the call drops abruptly around the minute mark. Though this needs to be investigated by the Aircall Support team (please report those calls for investigation), this may happen because the called telephone company does not send back any RTP (voice packets) back to the media server at all and the media server has a timeout set to 60 seconds. After 60 seconds of receiving no voice packets at all, the media server will disconnect the call. This depends on two things:

  • The timeout setting, which may change in the future (but is currently set at the above value).
  • The behaviour of the called party’s carrier, which sends back no RTP at all in that call scenario (that is not the case for all carriers, some do send some packets back to the calling side).

This is known to happen when calling Free mobile phones in France, for instance.