SIP (Session Initiation Protocol) is an Internet protocol for IP telephony, presence, instant messaging and audio/video conferencing. However, Ingate says its expansion has been limited by SIP not traversing current firewalls. The company says that its new firewalls are a remedy for this restriction, allowing SIP-based communication on secure private LANs over the Internet. Ingate produces SIP-capable enterprise firewalls that it says are a good fit for small to midsized businesses. The firewalls are a continuation of the Fuego firewall series, sold in the Scandinavian market for three years. Ingate will be launching its series of SIP-capable firewalls and firewall accessories over the next few months as the company expands in Scandinavia and enters the U.S. marketplace.