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IP-PBX systems and softswitches are in some ways apples and oranges. While in most cases softswitches are IP-PBX systems, the reverse is not always true.

When a system is referred to as an IP-PBX, that typically indicates only that the system supports VOIP communication to the handset and/or the PSTN (via something like SIP trunks). Avaya and Nortel have IP-PBX systems, along with a host of other established and new manufacturers in the telecom space.

A "softswitch" in the truest sense is a PBX that derives its feature functionality primarily from software. Voicemail, call handling, call center functionality, etc., are all implemented via software and use hardware only for basic connectivity to the PSTN or the handset. Asterisk is an example of a softswitch.

Softswitches are almost always IP-PBX systems, as this is the easiest way to avoid a reliance on specific hardware. Asterisk, for example, can operate as a pure IP-PBX softswitch on standard PC server hardware. Communication with both the PSTN and the handsets is accomplished via a software-based VOIP stack.

IP-PBX systems, on the other hand, are not always softswitches. Almost all IP-PBX systems offered by the hardware giants like Nortel and Avaya achieve their features via hardware -- expansion boards that fit into the main chassis. In my opinion, while these systems can derive some capabilities from firmware, it isn't proper to call such a system a softswitch.

There are also some hybrid systems like those from Vertical Communications and AltiGen. These systems are software-based in the sense that the majority of their features come from software running on a Windows Server PC, but with the exception of Vertical's HMP system they do require specific hardware to operate.

There aren't any capacity or capability limitations intrinsic to IP-PBX systems or softswitches given that we're talking about architecture, but the real-world implementations of softswitches can grow larger simply because they are sometimes used for carrier-level switching. Any capacity differences you see in the market are likely not the result of the technology but rather the marketing focus of the manufacturer (the SMB market is very attractive, but don't assume that just because IP-PBX systems are usually focused on the 25-250 seat size that you can't get them larger).

Connectivity to a third-party application server isn't something that would necessarily be impacted by the IP-PBX / softswitch distinction, as even most purely hardware-based systems these days support gateways that allow for integration with external application servers. That said, a softswitch will generally make the job far easier. Most softswitches include programming APIs that allow gateways to be programmed in a common programming language like VB or a .NET language. Asterisk is programmable if you don't mind getting your hands dirty, and both AltiGen and Vertical's TeleVantage include COM object-based SDKs that allow extensive control of the switches for the creation of IVRs and custom PC-based call management.

Contrast this with some of the proprietary script-based gateways of some hardware-based systems (including some hardware-based IP-PBX systems) where it's not a standard programming interface and the end-user is not able to modify the gateway without assistance (read: cost) from the provider.

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

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

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

a. convert the IP Phone calls to TDM calls to interface with PSTN Switches or other switches.

b. Switch calls within the phones of IP-PBX

A broad definition based difference is below.

Softswitch .....

A programmable network switch that can process the signaling for all types of packet protocols. Also known as a "media gateway controller," "call agent" or "call server," such devices are used by carriers that support converged communications services by integrating SS7 telephone signaling with packet networks. Using network processors at its core, softswitches can support IP, DSL, ATM and frame relay in the same unit.

According to the International Softswitch Consortium, a softswitch should be able to .....

(1) control connection services for a media gateway and/or native IP endpoints,
(2) select processes that can be applied to a call,
(3) provide routing for a call within the network based on signaling and customer database information,
(4) transfer control of the call to another network element, and
(5) interface to and support management functions such as provisioning, fault, billing, etc.

Software Makes It Flexible .....

The switching technology in a softswitch is in software (hence its name) rather than in the hardware as with traditional switching center technology. This software programmability allows it to support existing and future IP telephony protocols (H.323, SIP, MEGACO, etc.).

IP PBX ....

(Internet Protocol Private Branch eXchange) A telephone switch that supports voice over IP (VoIP). IP PBXs convert IP phone calls into traditional circuit-switched TDM connections for the PSTN. They also support traditional analog and digital telephones, allowing enterprises to migrate slowly to an all-IP telephony environment.

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

Michael is the owner of FreedomFire 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.

Article Source: http://EzineArticles.com/?expert=Michael_Lemm

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Posted by saqlain231

http://ezinearticles.com/?What-Is-The-Difference-Between-IP-PBX-And-Softswitch?&id=644546

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Posted by Hash007

I want to add more :
Soft Switch is a concept and future technology while IP PBX is solution or you can call it facility.

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Posted by waqqas1

Soft Switch is basically class 5 switch as well as called NGN switch which perform voip.
IP PBX are ued by AS for there own offices to facilitate there employer as well as to save money it is the concept of PABX

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Posted by HamidAliKhan

on the broad level IP PBX is used in enterprise enviorment whereas Softswitches are used for telecom service provider.

other techical differences are as follows:
1.Softswitch help in conversion of one type of signalline say(SS7 to SIP) for interworking between enviorments.
2.Media or bearer doesnt go through PBX only it helps in signalling setup whereas in Softswitch Bearer is handled by Media Gateway which is part of softswitch and media always pass via media gateway.
3. protocol supprted by PBX are very limited whereas Softswitch supports variety of telecom protocols

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Posted by bs_aggarwal

I am not a tech person, but to the best of my knowledge an IP PABX operates on IP platform, whereby the end desktop handsets has to be IP phone (at least have RJ45 points). it can only act as a PABX nothing more, but does everything on IP platform.

A softswitch is primarily used for call set-up. it also keeps track of the billing parameters (depend on brand/model). a Softswitch can be made to work like a IP PABX provided the necessary Universal Media Gateway (UMG) cards are installed. with the UMGs a Softswitch can also work as an IP PABX simultaneously. Thanks for the opportunity to share my view.

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Posted by william