The external call transfer – is the call transfer to a telephone line other than the company’s telephone line. The internal call transfer – the transfer of an incoming call to another addressee registered on the same telephone line.
This function available in some telephone networks allows redirecting the incoming call to another telephone, for example, a mobile phone, a box of voicemail or another telephone number where the called subscriber is situated. In such a way the subscribers can, for instance, receive calls that have arrived at their work number from their home or mobile phone.