I have a scenario where I need to make a call to a telephone(landline/mobile) or send SMS to a particular set of users only using ASP.NET and C#. The web application is not a mobile application.
How do I go about doing these? What typically would be the hardware requirements? I would be extremely grateful if you could provide me with pointers and reference websites.
Not sure if you're looking for hardware solutions to automate yourself, or external services. However, I've used BT's Web21C pretty extensively.
They have an excellent .Net API and a host of functionality. Their pricing is the best in the UK, but might fall down with US SMS, which is obviously cheaper - there are plenty of other SMS API providers though.
What BT do offer, which is rare, is an API interface for automating call dialling, conferencing and managing call flow.
Via WebServiceX, you can send SMS messages anywhere in the world. For phone calls I'd use Asterisk.
What exactly do you mean by "make a call"? Do you just need to call someone to transfer them or make your own custom, interactive automated call?
If you just need to make a simple call to transfer someone, there are services like VoiceStar that can do this. If you need to make a custom automated call, I would suggest OCS 2007 Speech Server. Asterisk is a SIP PBX and may or may not work for you depending on exactly what you're trying to do.
As far as sending text messages, I don't have much experience so others answers would probably be better.
messagepub, provides a single interface API to send not just SMS and make phone calls, but also IM, Twitter, and email messages. It might help you solve your problem.
They have a C# helper library that you could use to easily integrate multichannel messaging into your application.
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I had built one a while back using an SMS gateway server. This was done in .net 1.1,ASP.net & vb.net. If i remember correctly, i built up a simple webpage and posted my request to the sms gateway server via http post.
The webpage carried a simple textbox and a button to submit. Once that was done, posted the message. The packet included username & password for authentication & an sms message.
Hope this helps.