Cisco Supports International Signaling Protocol to Link Old- World Phone Equipment with IP Systems
November 2, 2004
By Jason Deign, News@Cisco
Cisco Systems® is helping European enterprises move from old-world, time-division multiplexing (TDM)-based private branch exchange (PBX) telephone equipment to next-generation Internet Protocol (IP)-based communications systems by supporting a common language protocol - Q.SIG - that bridges the gap between old and new communications worlds.
Both the Cisco CallManager 4.1 IP telephony system, launched this week, and the Cisco EGW 2200 enterprise gateway, unveiled earlier this month, include full support for the international standard protocol.
Q.SIG was developed in the 80s to enable the internetworking of enterprise PBXs. At that time, enterprises were beginning to link proprietary PBX platforms supplied by different vendors and needed a common language to allow them to communicate with each other.
That language, Q.SIG, also ended up providing the base for many voice network features, such as Calling Names and Call Completion, used widely by European enterprises.
Although support for a basic Q.SIG feature set has existed on Cisco CallManager since late 2002 with version 3.3, the release of the new CallManager 4.1 IP telephony system can handle practically all the features and functionality currently available to enterprises using TDM-based PBXs.
Adrian Brookes, IPT product manager for Cisco, says this means companies can start large-scale TDM-to-IP migration plans safe in the knowledge that their phone systems will not lose critical features and take advantage of new IP-enabled features available with Session Initiation Protocol (SIP) or H.323.
"The majority of IP telephony installations have been on green-field sites or in single office environments where full Q.SIG interoperability was not essential. Now that picture is changing, with many large enterprises wanting to move wholesale to IP.
"But this is not something they can do overnight. Having Q.SIG in their IP infrastructure means they can easily maintain all commonly-used features on their telephone systems while carrying out the changeover."
The case for IP telephony is now so compelling that at least two analyst firms, Synergy and Infotech, have predicted sales of IP PBX systems will surpass TDM systems in 2005.
Meanwhile, Gartner is predicting that by 2007 traditional vendors will have ceased development of TDM and will begin to pull back on the support of their TDM offerings. The reason is that IP provides features that are unavailable or too expensive to do with TDM equipment.
For example, IP allows enterprises to transmit high-quality video to every desktop computer in the company; the most that a TDM system will allow is low-quality video at 64 kbps.
The US has already seen some major switchovers from TDM to IP. Last month, for example, the Bank of America announced a rollout of 180,000 Cisco IP phones across 5,800 sites.
Of the nearly four million IP phones sold by Cisco to date, more than a quarter have gone to Europe, the Middle East and Africa (EMEA) and, says Brookes, there is growing interest in wholesale migrations from the region's enterprises.
Last week, for instance, the German consumer electronics retailer Media-Saturn announced it would be replacing its 40,000 phones with IP units over the next two years.
Elsewhere, however, it is possible some companies may have been stalling because of lack of full Q.SIG support on IP equipment.
The protocol is of particular relevance to the European market because it supports a number of features that are commonly used by businesses in the region, but not elsewhere.
North American enterprise employees, for example, are accustomed to using voicemail, which is easily supported on IP telephony systems, but the more personal nature of business relationships in countries such as Germany demands greater reliance on Q.SIG-based features.
These include Call Diversion and Calling Name or Alerting Name, which allows an employee to see who is calling (and who is routing the call) and thereby decide whether to take it or send it to voicemail.
Then there is Call Completion, which allows a caller to get an automatic ring-back from the person they are calling if that person is currently engaged or away from their phone; in the latter case, the system waits until the person's phone has been used again before setting up the call.
Finally, for network managers there is Path Replacement, whereby the network keeps track of where a call is being forwarded to and then cuts out any unnecessary points between the origin and destination, thereby keeping bandwidth use to a minimum.
Cisco has also introduced an IP version of Q.SIG with support for Annex M.1 in the H.323 specification so that Q.SIG features can be delivered between Cisco CallManager clusters.
According to market researchers MZA, up to 45 million extension lines in EMEA use Q.SIG or Digital Private Network Signalling System (DPNSS), an allied protocol that was defined by British Telecom (now BT) in the UK and which is also supported on the Cisco EGW 2200 gateway.
Not only is it widely used, but Q.SIG predates e-mail by about a decade so it is a familiar protocol for most network managers.
The version incorporated into the Cisco CallManager 4.1 and EGW 2200 gateway conforms to the International Standards Organization standard and also to those of the European Computer Manufacturing Association and European Telecommunications Standards Institute.
It is on top of a host of other features such as, in CallManager 4.1, enhanced security and greater integration and interoperability with other technologies. "This is not just about linking back to TDM; it is about pushing forward what we can do with IP," says Brookes.
Jason Deign is a freelance journalist located in Barcelona, Spain.
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