Callback service, not often used, but nevertheless implemented in the UniTalk service. Quite often, this service is used in taxi call services, call centers of some banks, online stores, etc. i.e., when you need to call the customer.
How the service works: with an incoming call from a client (most often there is a greeting and a notification that “wait, they will call you back”), then there is an auto reset, after which an outgoing call is made to the client.
To activate this service, in the section “IP-telephony” – “External lines“, opposite the number in the settings, check the box next to the “callback” service, and then select the audio file. If the audio file is not selected, then the incoming call will simply reset.