I understand that "at+sapbr" is used for setting up an HTTP or FTP connection and that "at+cstt" , "at+ciicr" etc. are used for just a TCP connection.
However, from what I understand, HTTP/FTP are just a layers on top of the TCP protocol. Why doesn't the SIM800 use "at+sapbr" for everything? Is there a difference in the way the SIM800 sets up the connection?
I tried different searches on Google, but I can't find a clear answer.