Need help finding multiple sms software

I wasn't sure where else to put this, it's not necessarily BlackBerry related.

I am looking for a good SMS software application.

I need to send multiple SMS notifications to multiple users across multiple carriers simultaneously via a single computer. Two way (receive) capability would be nice but not necessary.

I need something easy, functional, reliable, and tested.

I've googled, and looked at all kinds of crap on the net, but I really don't know what's good out there. They all make claims, and some appear to be quite cumbersome. This is going in a dispatch center, so I need it to be user-friendly and not too complex.

Thanks for the help.