Command Communications Comswitch 7500 4-Port Phone/Fax Modem/Ans Machine Line Sharing Device - 4 Port device (2 ports are linked) - For use with devices such as telephones, answering machines, fax machines, modems, etc. - Automatic or semi-automatic modes, Distinctive ring detection, Caller ID and voicemail compatible - DSL compatible, Stays on the line during every call - Works with two-lines, also two-line telephone compatible