Tough question without context. Abgriff when referring to electronics is usually a pick-up, so I think they're saying the mobile shares use of the car's antenna.

Looking at Bernd's link, the method of connection is inductive coupling, but the question is asking "How can I connect my phone to the antenna?"

For transformers, Abgriff is known as a 'tap' and that is engineerese for a connection.

If you want it simple, I would probably use this.