Response

The response is one of the following:

OK<CR><LF>
ERROR<CR><LF>
+CME ERROR: <cause_value><CR><LF>
+CMS ERROR: <cause_value><CR><LF>

"CMS ERROR:" is used as an error response for SMS related commands specified in 3GPP 27.005.

Some commands may also produce a varying number of information response lines before the final response. An information response can be received only when a command-specific response syntax is specified. An information response line usually starts with a prefix, which is the command entered:

+CMD: [...]<CR><LF>

Some commands may also produce notifications, which do not start with the command prefix:

AT+CGSN
490154203237518
OK