At some level everything has to go in a single band. I don't have separate network connections to my house, I don't send separate TCP SYN packets for each "band". I don't have separate storage devices for each file on my harddrive. We multiplex the data somewhere. Yhe trick to it is that the multiplexer has to be a component, and not a distributed set of ad-hoc regexes.
Strictly speaking, that only works with a three second delay between the third + (at which you receive “OK”, indicating a mode switch from data mode back to command mode) and the AT command (which is then interpreted as a command and not data).
Anything that would hang up on seeing that string as a monolith was operating out of Hayes spec.
