Hi

Just a thought, I could be wrong.
when you use hserin 1000, start, [wait("CMTI:"), skip 6, DEC2 sms_location, sms_location will contain a number, 2 digits say 01.
I have a feeling that the modem will require it passed in ASCII and not in the form its in.
when you do hserout ["AT+CMGR=1", 13, 10] I think it will send the 1 as ASCII $31 Decimal 49 and what your sms_location passes is ASCII char 11

Cheers Pete