It doesn't matter if the portmon sees the chars as bytes instead of "strings". Look at the first line of captured code: "41 54 0D 0A" This is just ASCII for "AT" and a CRLF.

Your Nokia won't mind the "gaps" in the flow. Just follow the commands and finish with the 0D 0A (enter).

Try a terminal emulation software (hyperterm?) and type AT + enter. You'll see the Nokia responds correctly. Now try typing AT more slowly, it still responds doesn't it?