Issue :: Sept/Oct 2004

  
Gateways of all kinds are becoming more versatile and scalable.

By Richard Grigonis

When a VoIP caller wants to talk to someone who owns a conventional circuit- switched phone (or vice versa), a device offering some kind of advanced “gateway” functionality between the two different networks is needed. The difference between the SS7 signaling of the PSTN and IP-based routing of next-gen networks is huge, making both media and signaling gateways a key component of the modern hybrid network.

Ironically, those businesses saddled with legacy phone equipment may think of a gateway as merely a small device attached to their PBX that can direct long distance calls over IP, perhaps serving to establish a remote office PBX extension.

The same can be said for residential subscribers to Vonage and similar services, who got their .rst impressions of VoIP by plugging their old analog handsets into a two-port Cisco ATA (Analog Telephone Adaptor) 186. Later, some of these same users may try bringing their SOHO or small business into the world of VoIP (and IP multimedia communications) inexpensively with an innovative “ADSL modem router” such as the Residential Gateway from Inventel, a French company. This is a device which supports up to eight concurrent virtual channels, has a fully configurable router and .rewall, integrates with Inventel’s innovative wireless Bluetooth and DECT phones, and supports a maximum throughput of 11 Mbps.

Larger businesses, of course, have gotten their feet wet in the VoIP waters by opting for vendors with reasonably substantial product lines, such as the MultiVOIP voice/fax-over-IP gateways from Multi-Tech Systems (Minneapolis, Minn.) which integrate voice and fax over the Internet or Intranet. The MultiVOIP family comes in analog and digital models ranging from one to 60 ports. MultiVOIP products connect directly to phones, fax machines, key systems, PSTN lines or a PBX. For Avaya Communication Manager environments, MultiVOIP extends and distributes the call features of a centralized Avaya media server and provides local of.ce survivability to branch offices of up to 15 users using analog or IP phones.

But a gateway does not have to be a standalone device–indeed, routers can be given software and/or hardware upgrades to “VoIP-enable” them, and the latest IPPBXs rely on integrated gateway functionality. Moreover, modern electronics allows such equipment to be an amalgam of both gateway and switching technology, such as ShoreTel’s ShoreGear Voice Switches, which are available in .ve different models to serve small, medium and large offices supporting IP phones, analog phones, analog trunks and digital trunks.

One could also place in this category Mitel Networks’ remarkably flexible 3100 and 3300 Integrated Communications Platforms (ICPs), which are “office-in-abox” VoIP solutions for the SMB market. They’re easy to install and maintain, yet even the small 3100 ICP contains call control software, a router, an eight-port Layer-2 switch and a data storage hard drive for voice mail. The 3300 model can handle anywhere from 30 to 30,000 users (when networked with other units), and even has an additional integrated 802.11 wireless gateway allowing mobile users to access data services and voice (via Mitel’s MINET wireless phones) anywhere in the enterprise. The Mitel ICP 3300 also can run such applications as a speech-enabled auto attendant and unified messaging; PDA and PC-based application integration; plus optional VoiceXML, contact center and CRM (Customer Relationship Management) applications.

A similar blurring of distinction is occurring with higher-end equipment found at service providers and large multinational enterprises. Perhaps the premier example of this is the Excel Switching Corporation (Hyannis, Mass.). Once known as the maker of the industry’s most powerful programmable “dumb” switches, Excel is in now rolling out some of the smallest (1U high) yet most featureladen multifunction platforms yet seen in the industry. These so far have included the basic AnyGen MSP 1010 that supports SS7-signaling, and the CSP 1010 that supports TDM links and media server functions.

Finally, in the first quarter of 2005, Excel will roll out the IMG (Integrated Media Gateway) 1010 which also handles both VoIP codecs and SIP (the Session Initiation Protocol), a call control protocol that’s fast becoming a favorite among makers of IP phones, IP PBXs and softswitches. Excel has decided to incorporate both signaling and media capabilities into its gateways, both to improve voice quality and to lower overall system costs.

“Our system can handle 672 DS-0’s worth of media gateway functionality,” says Mike Twomey, Excel’s VP of product marketing, “with additional horsepower for media processing, such as announcements, IVR capability, voice recording and conferencing. Plus we’ll have VoIP and SS7. That’s true across both the 1U platform as well as our larger 9U platform which supports up to 2000 channels.”

“For those who want to go with the new 1U chassis, we see it as being pretty cost effective down to the four-span level,” says Twomey. “And that can grow solely by software upgrades to 28 T1s or 22 E1s worth of capacity.”

Another across-the-board approach is taken by Cirilium Gateways of Tempe, Arizona, which offers branch office-sized (two, four and eight-port) SOHO gateways with PBX-friendly FXS, FXO and E&M interfaces; the medium-sized Series 8000 gateways; and powerful Signaling (SS7/C7 control) gateways for service providers and carriers. Many SMBs may .nd Circilium’s Series 8000 attractive, since this 19-inch rackmount handles digital interfaces, offers hot-swappable circuit cards and power supplies, and can be configured in density options ranging from one to 16 T1/E1 spans per card. High density Circilium gateways can support standard protocols such as MGCP, MEGACO/H.248, H.323 and SIP, as well as digital T1/E1 CAS, PRI ISDN and MFR2 termination.

And don’t forget Cirilium’s SIP Translator, which integrates SIP gateways and endpoints into the H.323 environment, and can also integrate older H.323 devices into the rapidly expanding SIP universe.

A three-level gateway product offering can also be found at Verso Technologies (Atlanta, Georgia): The entry-level Clarent Gateway 400 Internet Telephony Gateway, the medium capacity Clarent Gateway 800, and the high capacity Clarent Gateway 1200. The 1200 model scales from one span up to 12 spans within the same enclosure. Up to 360 ports of voice, real-time fax and data traffic can be active simultaneously in one gateway. Clarent ThroughPacket technology minimizes dropped or lost packets in the network and increases router efficiency. The 1200 also supports G.711, G.723.1 and G.729a codecs as well as Q.931 signaling. Other signaling support includes SS7/C7, PRI ISDN, T1, E1 and PBX connections.

Quintum (Eatontown, NJ) also has three classes of its Tenor MultiPath VoIP Switches: The Tenor AS Series (supporting two or four simultaneous VoIP calls), the AX Series (8, 16 or 24 voice calls) and the hefty DX Series (one-to-four T1, E1 or PRI spans). Quintum can offer VoIP gateway configurations that have equal numbers of PSTN and VoIP network ports to easily support PSTN-to-VoIP “gatewaying.”

In France, Cirpack is known for its wide range of softswitches capable of handling Class 4 and 5 traffic with simultaneous native support for TDM, ATM and IP networks and protocols. Complementing these is its scalable CIRPACK G16S Carrier-Class SIP Gateway, which connects a network operator’s SIP-based VoIP network to the PSTN. It can convert VoIP/RTP traffic to TDM circuits or ATM cells and offers transparent ISDN and SS7 trunking-over-IP to maintain legacy TDM services when using IP backbones for voice transit. It adapts to nearly any kind of local loop or core backbone, making it suitable for dealing with the telecom world’s current hodge-podge of optical fibers and mixed ATM, IP, and TDM (SS7) technologies.

Intelligent Access Devices

We’ll probably be living in a hybrid (circuit/ packet switched) network for a long time, 15 years or more. This will drive telcos to buy gateways with switching functionality–or is it softswitches with gateway functionality? But during the transition to IP, the accompanying adoption rates of broadband will fuel the sales of many smaller gateway-like IADs (Intelligent Access Devices) in the home and SMB market. These IADs will be designed not just to make a VoIP call but also to surf the web, download entertainment quickly and link up teleworkers with their headquarters. Even so, the formerly TDM-based IAD vendors will ultimately have to adjust their technology to a world increasingly dominated by packet-based voice, data and video.

For example, Verilink Corporation (Madison, Alabama) has introduced the 8000 Series of VoIP-enabled IADs, designed as an intelligent CPE-based device. The 8000 Series supports SIP and MGCP and provides a migration path from traditional telephony, Time Division Multiplexing (TDM) or Asynchronous Transfer Mode (ATM), to IP. The existing phones, PBX and Key systems can plug into the 8000 Series, which also supports various WAN interfaces, including ADSL, SDSL, G.SHDSL, T1 and E1 services can be configured, provisioned and managed remotely.

At the low end, Verilink offers their VIPER broadband IAD product family to service providers who in turn can bestow them upon their SOHO and SMB customers. VIPERs are ADSL and SHDSL IADs supporting both two and four ports of POTS or ISDN BRI applications with full Layer 3 Routing, Layer 2 Bridging and software security. VIPERs currently support Voice over DSL (VoDSL), but will soon be software upgradeable to VoIP.

Even smaller is the Model 2102 from Mediatrix (Sherbrooke, Quebec, Canada) which connects two residential phones or fax machines and a PC to a broadband modem, without the need for an external router. It even prioritizes voice traffic over data. The Mediatrix 2102 VoIP access device is equipped with two FXS ports and two 10/100 BaseT Ethernet ports.

Mediatrix also sells larger digital VoIPenabled “routers” for the enterprise, such as the Mediatrix 2500 series T1 PRI IP router and the 2600 series E1 PRI IP router. Both models combine VoIP and call switching with QoS access routing and VPN capability. The units are integrated IP routers with two Ethernet ports, a serial V.35/X.21 port and one or two ISDN T1 or E1 primary rate interface ports. This allows enterprise networks to connect to a service provider’s broadband access over DSL, cable or the wireless local loop.

The Future is Flexibility

As the silicon and software improves, vendors and service providers alike will try to outdo each other in terms of how quickly gateways can be configured and services created/provisioned. Even at the telco and service provider level, gateways will simply be large multifunction platforms near the edge that can be configured with additional softswitch or SBC functionality by plugging in the right mix of boards and/or software.

Board maker Artesyn Technologies (Madison, Wisconsin), for example, supplies components for big carrier gateways as well as boards for softswitch and signaling gateways. Artesyn has recently introduced new, powerful equipment based on the AdvancedTCA form factor, and can implement a media gateway on a single blade. They also offer solutions based on the current economical PICMG 2.16 “packet backplane” architecture (such as integrated softswitch/media gateway solutions). They also offer triprocessor CPUs for massive pure packet processing.

And last but certainly not least, the masters of packet-related hardware, AudioCodes (Israel and San Jose, Calif.), offer their VoP Media Gateway Modules, tiny mezzanine-sized boards ranging from low to super-high density and processing power (e.g., the TPM6300 board can handle up to 2016 channels of compressed voice). These boards are essentially building blocks used to construct such nextgen equipment such as media gateways, VoIP enabled class 4/5 switches, VoIPenabled conferencing bridges, IP PBXs, and VoIP enabled routers. AudioCodes hardware excels in voice compression, packetization, media processing, signaling processing and use of standard control protocols.

“Pigeonholding next-gen technology is not so easy, since with some devices you merely plug in whatever boards or add whatever software is necessary to achieve whatever set of functions you need,” says Excel’s Twomey. “It really just depends on the service provider–where they’re coming from, where they’re trying to go, how their network is laid out, and what the customer base looks like. I don’t think there’s one ‘right’ solution for everybody, but I do think there’s one ‘right’ solution per carrier. Some carriers want huge gateways with high-bandwidth, OC-12 interfaces, while other carriers are looking for something that can deal with just four T-1 spans’ worth of traf.c. And then there’s everything in between. You’re always going to have different solutions that are particularly suited for certain carriers.”
  

Richarg Grigonis can be reached at rgrigonis@vonmag.com.