Geeks Without Borders +) GWOBorg is an international coalition of passionate problem solvers working together to assist people whose survival is threatened by lack of access to technology or communications due to violence, neglect, or catastrophe.
One of the things that GWOB does is called The Digital Mountaintop: This is a free, open communications hub, accessible via voice, text (SMS), plain old telephone (POTS), Skype, SIP, Google Voice, Twitter, Facebook, Email, Instant Messaging (IM)…and as many other networks we can connect to. In crisis situations, neighbors can ask for help simply by sending sending a message to the DMT, as long as they (or someone they know) can connect via any of the messaging or real-time communication methods it supports.