Testing a connection to a TCP socket through SIM5320A cellular module
About the easiest way to get a response from a server is to do a HEAD request.

For example, open a socket to www.stackexchange.com port 80

Then send:

HEAD /about HTTP/1.1
Host: www.stackexchange.com
(blank line)


You should get a response back, but just the headers, not the whole page.

Something like:

HTTP/1.1 200 OK
Date: Tue, 31 Oct 2016 22:44:11 GMT
Server: Apache


etc.

I have used this just to get the current time off the network.