ViPR and IME

Packet over Wireless

ViPR and IME

By Michael Stanford  |  November 01, 2010

This article originally appeared in the November 2010 issue of INTERNET TELEPHONY

Back in March Cisco (News - Alert) announced an IETF initiative called ViPR, which standards for verification involving PSTN reachability, together with a Cisco implementation of the ViPR protocol, called inter-company media engine, or IME. ViPR seems designed to retrofit to SIP all the advantages that Skype (News - Alert) enjoys, like ease of setup, firewall and NAT traversal and distributed architecture. ViPR couples these improvements to the feature for which it is named, the ability to derive (securely) IP addresses from phone numbers.

ViPR is a potential game changer. It is hugely empowering to end users, especially enterprises that are looking for a low-cost, low overhead personal videoconferencing solution similar to Skype, but based on open standards. The Cisco implementation is a box that serves an entire local network, but the draft specification allows for ViPR to be implemented in a single PC, or even a phone.

Here's how it works: You make a phone call in the usual way. After you hang up, ViPR looks up the phone number you called to see if it is also ViPR-enabled. If it is, ViPR performs a secure mutual verification, and exchanges SIP URIs with the person you just called. The next time you dial that phone number, ViPR makes the call through the Internet rather than through the phone network, so you can do wideband audio and video with no per-minute charge. These subsequent calls bypass your telephone service provider, so don’t expect service providers to promote ViPR. 

The enthusiasts will be equipment providers like Cisco, and corporate IT departments looking for better unified communications solutions.

Service providers are likely to point out that since these calls are made over the Internet there are no QoS guarantees. But QoS issues are mainly due to congestion on the access link, and ViPR users will be able to beef up their bandwidth with the money they save on voice service.

If you are an IT manager looking to implement converged communications, ViPR is well worth investigating. Start by entering into your browser IETF draft vipr.

Michael Stanford (News - Alert) has been an entrepreneur and strategist in VoIP for more than a decade. (Visit his blog at

Michael Stanford (News - Alert) has been an entrepreneur and strategist in Voice-over-IP for over a decade. Visit his blog at To read more of Michael’s articles, please visit his columnist. Page.

Edited by Stefania Viscusi