First of all: never, never ever use delay instead of proper waiting by parsing the actual response given by the modem. See this answer for more details, including the point about waiting for "\r\n> " before sending data, which AT+CIPSEND
apparently shares behaviour with AT+CMGS
.
Then when you have fixed your AT command handling (see this answer for some hints), change SERVER IP
and SERVER PORT
to something that is open/not firewalled on your own PC (verify by checking at ShieldsUP). Run Wireshark while running the AT commands and verify that you receive the corresponding traffic. If everything is working as expected up till this point, then the problem appears to be with the server.