The page of the Nuvi 1100/1200/1300/1400 Owners Manual shows that the 1300 doesn't support Bluetooth. The 1310 and 1370 and 1390 do ,but not the 1300.
Since the manual covers all the 1xxx units it will talk about hands free and bluetooth but it may not be applicable to any one specific model.
There is probably a microphone in all the 1xxx models but only a bluetooth chip in some of them. There is physically no Bluetooth chip inside the 1300.