Now I am creating an iOS application. I also implemented some web services. My requirement is : "The user should be able to call a web service API by Sending a Text Message(SMS)". After a lot of research I found out that there a provider called Clickatell(http://www.clickatell.com/). But I don't know how can I configure it? Please help me in configuring this. Or Is there any other APIs or SMS gateways providing this service?
Disclaimer, I do developer evangelism part time at Nexmo.
Here are a few SMS APIs that I've used (I've not really used Clickatell, but I've gone through the signup process, and the following APIs seem a lot simpler to use):
All three APIs are straight forward REST/HTTP APIs.
You can call the API directly from your mobile application, however, you should consider if you really want to then compile your API credentials into your application. It may be better to host a kind pf proxy that your application uses - here's some example code used as a verification service, but it's essentially the same concept: https://github.com/Nexmo/Verify