The firm said that its SIP-7 services translate SIP-based VoIP traffic to ISUP (ISDN User Part), the part of the SS7 protocol stack used to set up and tear down circuits in a traditional PSTN voice connection.

SIP service providers can connect to the VeriSign SS7 network in this way, using a SIP soft switch and a virtual private network, reducing capital layout and time-to-market, the company said in a statement.