Intertex is a Swedish manufacturer of SIP aware ADSL routers, firewalls and broadband routers.
All Intertex products include a SIP proxy that could be used as a registrar as well as an outbound proxy.
SIP does not traverse conventional firewalls and NAT routers! Intertex products has a built-in SIP proxy and registrar that dynamically controls the frewall and NAT for full SIP support. What separates the Intertex products from most competitiors is that thay actually make SIP communication available to all devices on the LAN, whether they are softclients, SIP phones or ATA-boxes.