My client has a website but doesn't check emails often. He has a lot of web enquiries through the online contact form. He carries a mobile phone though. How to send contact form details that's submitted through the website to his mobile phone as SMS?
The quickest and cheapest way is to determine the email address for that person's phone. Almost every cell phone has an email address you can send to which will show up as SMS on the device. This should help you find the email address for each carrier: http://www.makeuseof.com/tag/email-to-sms/
If you want to send an actual SMS instead of an email, you could try a service like Twilio which makes sending and receiving SMS from your apps easy via a REST API. [Full disclosure: I work at Twilio, but I was a long-time satisfied customer before starting here.]