The TIME input is also a V/oct input (the faceplate marks it as V/8 TIME), so in modes like PLUME, sound/cycle & FLUME this input will control the pitch of Just Friends. In other sound generating modes an external VCO is required as a "driver" for the module.
Basic PLUMEry can be accessed without Teletype. As you said, Teletype opens up polyphony and other options/features within Just Friends but is hardly a necessity in this case.
