l vendor directory

Voice over IP
If there is one topic within the field of telecommunications for which hype has completely drowned out informed discussion, it must surely be voice over IP. In conference presentations, magazine articles and especially product brochures, voice over IP is invariably presented as the NEXT BIG THING. In addition to the "implement it now, don't miss the boat, don't risk becoming a technologically backward company" line, much of the discussion about voice over IP has presented it as an inevitability, something which all organisations will implement for all voice, the only questions being when and where, not if.

The underlying assumption, that all organisations will inevitably implement voice over IP and that all voice will be carried by IP networks, is false. Negative. Untrue. This is what comes out of the north end of a bull facing south! That's not to say that many organisations will make some use of voice over IP - many will - and that there aren't a number of useful applications of voice over IP - there are - but like all other claimed-to-be revolutionary technologies, voice over IP won't replace the other existing technologies use to carry voice, VoIP has simply taken its place on the technology smorgasbord and has done so without knocking any of the others off in the process.

As most visitors will be aware, Internet protocol (IP) is the network-layer half of the TCP/IP pair of protocols that are the dominant layer 2 and 3 protocols used on enterprise LANs and WANs, and is also the network-layer protocol of the Internet. By encapsulating voice into IP packets, voice can be carried on such networks. And as there is more than one application of IP, there is more than one application of VoIP - I've come up with the following four:
l Carriage of voice within a LAN-based telephone system;
l Carriage of voice through an organisation's private wide-area network in addition to data for which it was most likely to have been constructed;
l Carriage of voice through the Internet;
l Carriage of voice through an ISP-managed, Internet-based VPN.

These will be discussed briefly below.

Unfortunately, some vendors are confusing the issue by defining pseudo-categories into which they are "classifying" their products. One such term is IP-PBX or IP-PABX. The reason I won't use it is that it is inherently confusing. A PABX, even one that supports IP extensions and/or IP trunks, cannot be claimed to be an IP PABX, as it internally uses TDM, not IP. Similarly, although a LAN-based telephone system does use only IP to switch voice, such a system is not a PABX. Therefore, I won't use this term. For a list of telephone systems of all types including LAN-based telephone systems, visit the Telephone Systems page.

LAN-based Telephone Systems
As the name suggests, LAN-based telephone systems are premise-based telephone systems that use an IP LAN to carry voice. Of between 19 and 20 such systems from developers around the world, six have a presence in Australia and New Zealand.

But such systems are not the only ones to use the LAN to carry voice. Most of the PABX systems also support an interface to a LAN to which telephony-enabled PCs and IP handsets can be interfaced. But why? Of course, this gives users another option, but one cannot escape the conclusion that there is as much of a "me too" factor as there is a response to a genuine need. An organisation considering this option would be advised to state its requirements in terms of capabilities, features, reliability etc. but not specify a technology or architecture, and let vendors propose solutions that address the specified requirements. (See How to write an RFT).

If a vendor was to determine that its bid would be more cost effective and/or a better fit to requirements using IP extensions, the RFT should allow such a bid. But if the vendor was to determine otherwise, the RFT should similarly allow a bid using analogue or digital extensions.

A list of the LAN-based telephone systems can be found on telephone systems page.

Voice through a Private IP Network
It is generally accepted that a traditional TDM-based private voice network in which each call uses a 64 kbps circuit for the duration of the call is not an effective use of resources. Thus, technology and suppliers have developed a number of alternatives, one of these being to convert voice to packetised IP and transmit it through the organisation's private IP network. To do this, one can use IP trunks, which some PABXs support, gateways, or voice-capable routers. A list of such gateways and routers appears below.

Voice through the Internet
With the exception of its use by some collaborative browsing products, voice through the Internet is not applicable to enterprise communications.

Voice through Public IP Networks
Some carriers, ISPs and other service providers offer voice through virtual private networks (VPNs) and other services. This site does not currently list carriers, ISPs and other service providers.

Consulting Projects Involving Voice over IP
Occidental Communications has undertaken a number projects involving the carriage of voice through packetised networks, including frame relay networks, ATM networks and IP networks. These have included assessing the cost-effectiveness of using such networks to carry voice and advising on the technical factors that must be addressed to ensure it will work.

Vendor Directory - Gateways and Voice-capable Routers

Omni/Switch Router and OmniAccess 512 from Alcatel-Lucent
Switch/routers with analogue and E1 voice ports.

S8300, S8700, S8400 and S8700 Media Servers from Avaya
Media servers which can support up to 333 E1 ports or up to 4,000 analogue circuits.

1750, 2600, 3600, VG200, VG248, 7200, 7500 and Cat4224 from Cisco
Routers with analogue, BRI, PRI and/or E1 voice ports.

Catalyst 4000 and Catalyst 6000 from Cisco
Gateways with analogue, PRI and/or E1 voice ports.

Opencall Multiservice Controller from Hewlett Packard
Service gatekeeper for IP networks supporting voice

NetSpire MGU from Open Access
Gateway with 4 analogue ports.

Smartnode 1200, 1400, 2300 and 2400 from Patton-Inalp, distributed by Emtec
Gateways which can support from 1 analogue port to 4 E1 ports.

MultiVOIP range from MultiTech, distributed by Norcom
Gateways with E1 or up to 60 analogue voice ports.

Multiservice Access Switch 4400 (formerly named Passport) series from Nortel
Gateways with analogue and E1 voice ports.

BV 1250 from Oki Network Technologies, distributed by IPL Communications
Gateway with four analogue voice ports.

Tenor CMS from Quintum Technologies
Gateway switch with up to 32 E1 ports per chassis.

Tenor MultiPath Switch from Quintum Technologies
Router with 8 analogue voice ports or 1 E1 port.

Tenor A200 from Quintum Technologies
Router with 2 analogue voice ports.

Vega 50 6x4 VoIP Gateway from VegaStream
Gateway with up to 24 analogue ports, up to 16 basic rate ISDN channels or combinations of either type.

Vega 50 BRI VoIP Gateway from VegaStream
Gateway with up to 8 basic rate ISDN channels.

Vega 5008 VoIP Gateway from VegaStream
Gateway with 8 analogue voice ports.

Vega 5024 VoIP Gateway from VegaStream
Gateway with 24 analogue voice ports.

Vega 5048 VoIP Gateway from VegaStream
Gateway with 48 analogue voice ports.

Vega 400 VoIP Gateway from VegaStream
Gateway with up to four E1 or T1 ports.

Articles on Voice over IP

Voice Over IP Arrives Australian Communications June 1997

Ebony and Ivory, Carrying Voice on Data Networks Australian Communications April 1998

PABX Gets TCP/IP Support Australian Communications August 1998

The Many Applications of Voice over IP Australian Communications March, 1999

Using Packet-Switching for Voice Insight IS [UK] June, 1999

Voice over IP CRM January 2000

Using Packet Switching TCP/SNA [UK] March, 2000

The IP PABX: All Operators Busy CommsWorld June, 2000

Voice over IP Telcall October, 2000

Will Cisco Fly in the Enterprise Telephony Market? CommsWorld June 2001

Note that this site is not sponsored. Vendors are included because they develop and/or distribute products in Australia and/or New Zealand which fall within the specified categories. Many of the vendors listed herein also have other products. Vendors seeking inclusion click here. Finally, note that Occidental Communications does not sell these or any other products.

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Occidental Communications, 2009