It is more necessary on IP than on ISDN since there are sniffers that can sniff for IP packets.

We have done testing for the US DoD with bulk encryptors for IP.

Companies such as Fortress Technologies (http://www.fortresstech.com/) make very good encryptors for non-government applications that we have tested with our products.

Motorola also makes equipment, but I do not know that it is available to customers outside the US DoD.

Because COTS encryption technology is generally geared to encrypting high capacity trunks (T1, T3, 10/100 Ethernet), the cost (latency) of encrypting VTC data is typically nominal - we run at comparatively low bitrates.

I have not had any **** customers report VTC problems as a result of IP encryption, but there are considerations when implementing cryptographic devices for VTC in an IP environment. Most encryptors will preserve timing and framing data, but depending upon the placement of the device in the network topology, effects on other variables may be serious. Consider for example, that most IP encryptors bulk encrypt everything (including IP headers) which can kill all the QoS mechanisms that may be in place (routers will be able to route traffic, but data bits in MAC addresses used for IP precedence will be scrambled and thus unusable for QoS prioritization). Some vendors, like Lucent (I think...?), have technology that encrypt the IP packet while passing critical IP header data needed for QoS in environments using switches like Cisco. Food for thought...