aq_mishu:
OK, basically I wanted the GSM to be fully independent, because that's how i can leave the delay(5000) away from the main CPU.
Why would you use delay(5000) ?
You can manage timing without blocking using millis() as illustrated in Several Things at a Time
Edit to insert the correct link above. The following link was wrong - sorry for any confusion (senior moment 
)
Serial Input Basics
...R