Hi,
here's the solution to convert (USA) t-mobile 1616 models,
and probably vice versa (normal 1616 to 1616-2c)
(Method should be applicable to all similiar Infineon models - 1800, c1-00, etc etc.)
1. backup full PM
2. backup RPL, and on cyclone backup IMEI pm
3. Flash RH-125 firmware with desired lang. pack
4. write attached PM (for 900/1800MHz band, for rh-125)
5. check imei etc, if needed, write back original RPL / imei PM
6. change marked filter (check on image attached) from similiar model
voila ... full signal bar, phone works normal.
p.s. you can probably use filter from different models, i used from c1-00,
but any dual-band filter same size/pinout should work.
p.s.2 i missed thread title, it's RH-125, not rm-125
press THANKS button if this was usefull.
have a nice day
b.r.
ALex