>I have a motorola droid 4 here; it uses gsm 07.10 multiplex. Over >that, there are AT commands, but prefixed with serial numbers, in >U0001AT+FOOBAR form. Corresponding reply then has U0001 prefix, too. >Has anyone seen that before? Any hints for me trying to add the >support? > I've never seen anything like it. The 07.10 was explicitly designed so that the AT command processor didn't need to know or care whether it was connected directly to the serial port or to the multiplexer. E.g. AT commands should not be modified in any way. Are you use this is a 07.10 multiplexer and not something else? What is the serial number exactly? Serial number of the multiplexer channel or ?