The Set command activates/deactivates the
specified PDP context(s). When the command is
completed, the ME remains in V.25 command
state. If any PDP context is already in the
requested state, the state for that context
remains unchanged. If the requested state for
any specified context cannot be achieved, an
ERROR or +CME ERROR response is returned.
Extended error responses are enabled by the
+CMEE command. If the ME is not
GPRS-attached when the activation form of the
command is executed, the ME first performs a
GPRS attach and them attempts to activate the
specified contexts. If the attach fails, the ME
responds with an ERROR or, if extended error
responses are enabled, with the appropriate
failure-to-attach error message.