Custom ringtones revert to Nokia standard

A. This is easy to solve, but it's worth taking a moment to think about what your phone's having to do when a call comes in. In addition to accessing your Log (to record the call), it has to perform a lookup in your Contacts, in order to display the caller name, if known. And, on top of that, you're asking it to go off, find an MP3 file, load it up and start decoding its music data. And all of this has to happen in the first second or so after an incoming call is detected, which understandably is a lot for a mobile phone processor to handle. And when it can't do everything in time, the least important gets dropped, in this case accessing and playing the custom MP3.

Your MP3 ringtone is probably on expansion card, which is slower to access than internal 'memory'. You can make one part of the above procedure faster by moving the MP3 file onto 'Phone' and then pointing your profile at the new location. You can also help out by going into Log and setting 'Log duration' to '1 day' instead of the default of '30 days'. With these two changes your smartphone should remember your ringtone setting and generally cope better when a call comes in.