I just bought a house that came with an operational Panasonic 308 Easaphone. I would love to set up handsets in some rooms to use as an intercom - we don’t use a landline so no need there. I can’t figure out exactly what handsets are compatible. Do newer Panasonic cordless phones work with it? I’ve seen mentions that the phone needs to be a KX line, but those seem to all be old school office lines, definitely don’t want those.