Hi Billy,
No need of using MAX232 IC.If your controller source voltage is more than 3.3V then use SN74LVC4245A bidirectional voltage level translator in between your controller and phone to communicate.
Regarding PDU format, you need to decode the received message fom PDU format, this can be done in coding.
Suggest you to go through the PDU format & understand the bit by bit data.
Example:
PDC CODE: 0891683108200805F01151048181160000FF16C8329BFD66B5F320B8BC4CA7E741F7B79C4D0E01
08: Length of Service Center Number
91: Indicate there is a plus at the beginning of Service Center number
683108200805F: Service Center number: 8613800280500 Note when the length
of number is an odd number, add F.
11: Indicate this SMS will be sent.
51: TP-MR Message Reference, not common used.
04: Length of destination number. Here 1861.
81: No plus here.
8161: Destination number 1861.
00: TP-PID.
00: TP-DCS. TP-UD is coded by 7bit character method.
FF: TP-VP. Valid Period. Here is infinity.
16: Hex value equals to 22. This indicates there are 22 characters in TP-UD
C8329BFD66B5F320B8BC4CA7E741F7B79C4D0E01: TP-UD, decode it using 7bit character method.
Any more info needed kindly post.