Ok, I think I have got your point. I read somewhere that it is advisable to write "0" to all EEprom locations before attempting any write statement. Is it true?
I will otherwise remove statements writing "0" to locations before an sms is received and after and sms is processed and system is ready to receive the new one.

Also I wonder why ph1 locations 0 to 12 gets first 3 digits as 0. As far as overwriting is concerned there are no locations -3,-2,-1 for me to make a mistake and shift 3 places forward?