Question about Gigaset CL390A Duo

The telephone does not have a plug but the Dect antenna and this has the RJ-11 plug. It looks like a network plug (Lan) but only with 4 pins.

As described by the previous speaker, the Gigaset comes with an RJ11 cable to connect the phone directly to the Internet Box. BUT an AVM telephone adapter is also included in the scope of delivery and can thus be connected to the original TT83 socket. Greetings