OpenGGSN

OpenGGSN is an implementation of the Gateway GPRS Support Node ( GGSN) element in the GPRS core network.

It's available under GNU GPL and has its homepage at  http://sf.net/projects/ggsn

OpenGGSN was developed in 2002 to 2004 by Mondru AB and was abandoned for some years before adopted by the Osmocom project.