1. CIMD Computer Interface to Message Distribution
   Promoted by Nokia with openly available specifications and widely used.

2. SMPP http://en.wikipedia.org/wiki/SMPP
   There is huge, matured and widespread acceptability of SMPP standard across telecom industry. SMPP approved by ITU (International Telecom Union) for SMS.
   URL http://opensmpp.logica.com/introhtml/menu.htm contains specification of SMPPv3.4 and library, simulator, and test-program from Logica promoter company.
   URL http://smppapi.sourceforge.net/ is another good library to be used. I donot recommend because it is too lengthy where Logica library is very much abstract to developers

Current implementation requires a compatible modem on serial-port which may not be choice for many of network admin. I can understand that if there is network outage then no SMS alert will be received by admin but then it is good to have alert for other outages