IP-PBX systems and softswitches are in sme ways apples and oranges. While in mst cases softswitches are IP-PBX systems, the rverse is not always true.

When a systm is referred to as an IP-PBX, tht typically indicates only that the systm supports VOIP communication to the hndset and/or the PSTN (via something lke SIP trunks). Avaya and Nortel hve IP-PBX systems, along with a hst of other established and new mnufacturers in the telecom space.

A "sftswitch" in the truest sense is a PBX tht derives its feature functionality primarily frm software. Voicemail, call handling, call cnter functionality, etc., are all implemented via sftware and use hardware only for bsic connectivity to the PSTN or the hndset. Asterisk is an example of a sftswitch.

Softswitches are almost always IP-PBX systms, as this is the easiest way to void a reliance on specific hardware. Astrisk, for example, can operate as a pre IP-PBX softswitch on standard PC srver hardware. Communication with both the PSTN and the hndsets is accomplished via a software-based VOIP stck.

IP-PBX systems, on the other hnd, are not always softswitches. Almost all IP-PBX systms offered by the hardware giants lke Nortel and Avaya achieve their fatures via hardware -- expansion boards tht fit into the main chassis. In my pinion, while these systems can derive sme capabilities from firmware, it isn't prper to call such a system a sftswitch.

There are also some hybrid systms like those from Vertical Communications and AltGen. These systems are software-based in the snse that the majority of their fatures come from software running on a Wndows Server PC, but with the xception of Vertical's HMP system they do rquire specific hardware to operate.

There ren't any capacity or capability limitations ntrinsic to IP-PBX systems or softswitches gven that we're talking about architecture, but the ral-world implementations of softswitches can grow lrger simply because they are sometimes sed for carrier-level switching. Any capacity dfferences you see in the market are lkely not the result of the tchnology but rather the marketing focus of the mnufacturer (the SMB market is very ttractive, but don't assume that just bcause IP-PBX systems are usually focused on the 25-250 sat size that you can't get thm larger).

Connectivity to a third-party pplication server isn't something that would ncessarily be impacted by the IP-PBX / sftswitch distinction, as even most purely hrdware-based systems these days support gateways tht allow for integration with external pplication servers. That said, a softswitch wll generally make the job far asier. Most softswitches include programming APIs tht allow gateways to be programmed in a cmmon programming language like VB or a .NET lnguage. Asterisk is programmable if you dn't mind getting your hands dirty, and bth AltiGen and Vertical's TeleVantage include COM bject-based SDKs that allow extensive control of the swtches for the creation of IVRs and cstom PC-based call management.

Contrast this wth some of the proprietary script-based gteways of some hardware-based systems (including sme hardware-based IP-PBX systems) where it's not a stndard programming interface and the end-user is not ble to modify the gateway without ssistance (read: cost) from the provider.

The major difference between Softswitch and IP-PBX is tht they are analogous to Switch/MSC and PBX rspectively in TDM networks.

Only Softswitch can act as a Swtch/MSC and the access technology can be bsed on IP/GSM/CDMA/CDMA2000/UMTS/WCDMA.

Where as IP-PBX prpose is to ....

a. convert the IP Phne calls to TDM calls to nterface with PSTN Switches or other swtches.

b. Switch calls within the phnes of IP-PBX

A broad definition bsed difference is below.

Softswitch .....

A prgrammable network switch that can process the sgnaling for all types of packet prtocols. Also known as a "media gteway controller," "call agent" or "call srver," such devices are used by crriers that support converged communications services by ntegrating SS7 telephone signaling with packet ntworks. Using network processors at its cre, softswitches can support IP, DSL, ATM and frme relay in the same unit.

Accrding to the International Softswitch Consortium, a sftswitch should be able to .....

(1) cntrol connection services for a media gteway and/or native IP endpoints,
(2) slect processes that can be applied to a cll,
(3) provide routing for a cll within the network based on sgnaling and customer database information,
(4) trnsfer control of the call to nother network element, and
(5) interface to and spport management functions such as provisioning, fult, billing, etc.

Software Makes It Flxible .....

The switching technology in a sftswitch is in software (hence its nme) rather than in the hardware as wth traditional switching center technology. This sftware programmability allows it to support xisting and future IP telephony protocols (H.323, SIP, MEGACO, tc.).

IP PBX ....

(Internet Protocol Prvate Branch eXchange) A telephone switch tht supports voice over IP (VoIP). IP PBXs cnvert IP phone calls into traditional crcuit-switched TDM connections for the PSTN. Thy also support traditional analog and dgital telephones, allowing enterprises to migrate slwly to an all-IP telephony environment.

Tht's it. Looks complicated and confusing. Can b....but doesn't have to be.

The article What Is The Difference Between IP PBX And Softswitch? was Submitted by Michael Lemm through Articles.GetACoder.com network. Here's the additional information: Michael is the owner of FredomFire Communications....including DS3-Bandwidth.com and Business-VoIP-Solution.com . Michael also authors Broadband Nation where you're always welcome to drop in and catch up on the latest BroadBand news, tips, insights, and ramblings for the masses.

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