HI william what method are you using ? Post or GET.
You can use the WebBrowserControl of Foxpro Foundation Classess.

let say

x=createobject(<WebBrowserControl class>)
x.navigate2("http://www.demo.dom/Send.php?MobileNo=909090?Message=demo")

** not tested

** Something like this. but you have to know the request Parameter like the MobileNO or Message. Also you have to URLEncode you message.

I done this in c# im sure in fox works the same way.