SMS - Incoming Message Processing

I'm looking for some recommendations on 'renting' a SMS processing gateway.

Basically, (without going into the full details) i want my clients to be able to send a formatted txt from their mobile (generic technology) to a SMS gateway (via a service number). I then would like this gateway to run a http (or https) command to populate a database located within our domain. The end game is that this txt creates a request that initiates a workflow.

Now, I don't yet have a full requirements spec other than the fact that we will have to use a mobile to initiate the workflow as access to the internet will not always be guaranteed (we are operating in some of the most remote and hostile environments on old mother earth!!).

Has anyone used any sms service that is both simple and inexpensive and more importantly, isn't tied to a contract that involves requiring 000's of txts per month (this will at most have 10-20 txts per day, so not a money spinner for the mobile/gateway owner).

We will be implementing the domain side in .net and are comfortable in that technology. So whether the http message is xml/json or simple querystring parameters, we're not concerned. The main concern is that we have recommendations for a robust service gateway that receives messages and runs the http command in any format that we specify.

Looking fwd to suggestions and thoughts.

[update] - our preferred service provider would be UK based as the operation would be very much driven by UK开发者_如何学编程 daylight hours

Check out Clickatell (no affiliation). It has a excellent API and is realtively inexpensive. The quality of text messages sent worldwide is very high in my experience (very high % get through).