Mp3 ringtone problem - moto v3

Help, having spent the last couple off hours trying to put a simple mp3 ringtone onto the wifes Motorola v3 phone have now given in and am now looking for some kind sole to put me out the misery I am going thru !!!

okay mp3 file 5 mb in original size , manged to get the size down to 856 with the aid off a few software programmes and looking to use as ringtone, no matter what I do I keep getting the message " request denied by phone required entry too large ( 0x40D ) now I know the phones memory is small but it is certainly not full enough not to accept any further ringtones or whatver so as far as I know its not the phones memory that is the problem, have tried motorolas own ringtone converting software without and joy and also too other ringtone conversion software programmes but keep getting this same message when it comes to transferring the actual file.

the original mp3 file playes fine on the pc so no probs there either.

Help any suggestions ??