edge stps (signal transfer points) are networking hardware devices embedded with software that performs routing, signaling, firewall, and packet conversion functions. their primary purpose is to unify networks that use various transports and signaling protocols – such as ss7, sip, sigtran, tdm, ip, etc. – into cohesive service environments. unified environments are simpler for telecommunications companies to manage, and also enable them to cost-effectively transition to next-generation networks based on the internet protocol (ip).