I'm building a serial cable between 9210i and my GPS device.

I have one GPS provider's document stating that I should apply +3...15V between DTR-2L's pins 4(DTR) and 5(gnd).

Document found from the forum (Nokia_DLR-2L.pdf) says: "NOTE1: ...DTR and/or RTS must be activated (have positive voltage) in the connected device..." , but the document does NOT spec the range accepted.

What's the maximum voltage I can apply to DTR-2L cable's pins, which is supposed to powerup the serial interface in the phone(9210i). Can I apply 12V+ (car usage?)

Can anyone confirm or give me the pointer to the documentation describing electrical specs for DTR-2L.