Bulk SMS Management

So in the wake of yesterday’s shooting, I am researching for a basic web-based SMS management system for a small group of 30-40 non-techie people who have various personal mobile plans. Preferably LAMP backend, not really plugged into any other systems at this stage, self-sign-up, very basic features and functions, kind of thing. Might want to expand it to more affiliated groups in the future, if it gains any attention here. So far I’m seeing a few interesting possibilities on Sourceforge that I may begin to try out today or tomorrow. Peer-to-peer is also viable as a second choice, if such a thing makes sense. Any recommendations?

Short form: It isn’t going to be easy because telcos don’t want to accept a lot of outside SMS traffic.