|You post is a bit confusing. Cat5e is a cable specification. You say there is no jack for the cable. |
What jack? the one in the wall.
It appears you have a RG45 socket in the wall. Is ther any cable connected to this socket. What you plug into the socket is dependant on what is on the other end if anything.
The Modem connects to a telphone socket if it is ADSL via an RG11 soket which is like an RG45 but slightly smaller. If it is a cable Modem then you need a cable termination and that usually connects vis co-axial cable.