Deciphering pinout of USB to serial cellphone cable?

[bizzybody]

I have a USB to serial cellphone cable with this connector. http://pinouts.ru/connector/18_pin_Samsung_cell_phone_special_connector.shtml

What I can't figure out is exactly which of all those pinouts it's wired up as because I don't know what phone it was originally used with. It has a lump in the middle with a Prolific USB to Serial converter. I'd have to break that to get it open.

I do know it DOES NOT WORK with a Samsung SCH-A650, it actually makes the phone act like the charger is plugged in, even when the USB end is not connected to anything. I installed drivers for the Prolific converter, which appeared to be recognized fine. (Finding the right Prolific drivers for Vista was not easy!)

What I'd like to do is remove the phone connector and solder it to a normal USB cable to make a data cable for my A650 phone, but I don't know if it'll work just connected directly or if it needs some pins shorted or other extra circuitry to enable things like uploading ringtones. I had borrowed a Mobileaction cable, which had a large USB plug and I had to install drivers- but I don't know if the cable itself actually had any active chip or circuitry in it or if the drivers on the Mobileaction CD were really for the phone instead of the cable.

I'd be experimenting already, but I'd really like to be able to salvage the USB to serial conversion part for building a GPS reciever for my laptop from an OnCore module from an obsolete OnStar system. Thus the need to decipher the existing pinout of the phone end of the cable.

The cable was free, so making it serve two needs would be twice as good as free! :)