In SMS - SMS Settings - HTTP to SMS, please click Advanced, make sure debug and timeout are greater than 0, then save it.
And please add me to your skype contact list, my skype is along.zou, named Michael.
The correct usage is http://172.16.179.1:80/sendsms?parameters, not http://IP/smssend?parameters.
Please check it and try again. If you still have problem , please contact me. My contact info is shown as below.