This is a simple project for one winter night when you have nothing better to do. Parts will not cost all that much, so you will save money by building the cable yourself. This also works with everything I tried on my 6150 phone.

The original schematics was based on MAX232 which could use 3V zeners on FBUS lines. I opted for 3232 instead. Also, diodes were expensive Schottky diodes in orignial but most anything works just as well.