The WIP User Guide says that, once an HTTP Session Channel has been established, it should be possible to issue multiple HTTP requests without needing to close the Session.
This did used to work in WIP v3.01, but no longer works in v5.10 - see: https://forum.sierrawireless.com/t/multiple-http-requests-every-other-one-fails/4184/1
Hmmm… someone else has problems in v5 with code that worked in v3:
I think the problem still exists in WIP v5.20, and not only with a HTTP session.
I’m trying to set up multiple data requests to read out multiple emails from an inbox via a POP3 session. The first request goes correctly, but the following requests fail.
Problem solved 
The problem was that I tried to open a data channel to quickly after a delete action of the previous email. A timeout of 1 sec did the trick.