To determine the value of each bit in a byte.

[optio]

Shift n bits -1 right (bitwise >>) to get bit at position from right to left and check with bitwise & 1.

Now I’m starting to understand your PDU reading code.

Mostly is not mine , it’s taken from http://forum.mikrotik.com/t/script-for-sending-incoming-sms-to-mail-with-full-parsing/140125/1 but I understand enough to adapt it for my purpose.