To answer another part of the querry:

I went to a radio station once and I found the presenter receiving texts from listeners from an inexpensive Nokia phone to a PC where he was reading the song requests/feedbacks and echoing them to the listeners [if it was not 1100, it was a phone with the same look]..

I asked whether he has anything other than the phone and the PC and he said that was just it... No 4 digit code, just the number he kept repeating to his listeners.

Of cos it would be prudent to choose a very simple number like 073X 650 850 etcetra  - if you do not want to use a 4 digit code...