Do you mean can you use cat6 as telephony calbe (with appropriate plugs/sockets at each end) or do you mean can you carry the telephone calls over an IP network.
If it is the former then the switches are irrelevant - the cable doesn't plug in to any active equipment. Use standard telephone sockets at each end and you can carry the call over cat6 cable.
If you meant the second option then you would need equipment to turn the call into an IP call. I suspect this isn't what you are trying to do. But if you want to carry both network and standard telephony over the same piece of Cat6 then you would have to have a PBX of some kind to turn the incoming telephone line into a VoIP service.
EDIT : One other option that might work is to use some of the pairs in a Cat6 to provide the data and a separate pair to provide the telephone. That way you could use a single cable to do both but would have to split the pairs out at each end to the separate types of socket.
Edited by ian72 (Fri 07-Dec-18 15:00:13)