What is the difference between IP PBX and Softswitch?
IP-PBX systems and softswitches are somewhat apples and oranges. Although in most cases the softswitches are IP-PBX systems, the opposite is not always the case.
When referring to a system as IP-PBX, that usually indicates only that the system supports VOIP communication with the phone and / or the PSTN (via something like SIP trunks). Avaya and Nortel both have IP-PBX systems, along with a number of other new and established manufacturers in the telecommunications industry.
A “softswitch” in the true sense is a PBX that derives its functionality primarily from software. Voicemail, call handling, call center functionality, etc. are implemented through software and use hardware only for basic connectivity to the PSTN or phone. Asterisk is an example of a software switch.
Softswitches are almost always IP-PBX systems, as this is the easiest way to avoid dependency on specific hardware. Asterisk, for example, can function as a pure IP-PBX softswitch on standard PC server hardware. Communication with both the PSTN and phones is accomplished through a software-based VOIP stack.
IP-PBX systems, on the other hand, are not always soft switches. Almost all IP-PBX systems offered by hardware giants like Nortel and Avaya achieve their functions through hardware: expansion boards that fit into the main chassis. In my opinion, while these systems may derive some capabilities from firmware, it is inappropriate to call such a system a software switch.
There are also some hybrid systems like those from Vertical Communications and AltiGen. These systems are software-based in the sense that most of their features come from software running on a Windows Server PC, but with the exception of Vertical’s HMP system, they require specific hardware to function.
There are no capacity or capacity limitations intrinsic to IP-PBX systems or softswitches since we are talking about architecture, but real-world implementations of softswitches can grow simply because they are sometimes used for carrier-level switching. Any capacity differences you see in the market are likely not a result of the technology, but rather the manufacturer’s marketing approach (the SMB market is very attractive, but don’t assume that just because IP-PBX systems they generally focus on the 25-250 seat sizes that cannot be made bigger).
Connectivity to a third-party application server is not something that is necessarily affected by the IP-PBX / softswitch distinction, as even most purely hardware-based systems these days support gateways that enable communication. integration with external application servers. That said, a softswitch will generally make the job much easier. Most softswitches include programming APIs that allow you to program gateways in a common programming language such as 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 switches for IVR creation and custom PC-based call handling.
Compare this to some of the proprietary script-based gateways on some hardware-based systems (including some hardware-based IP-PBX systems) where it is not a standard programming interface and cannot be modified by the end user. Gateway without help (read: cost) from the provider.
The main 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 Switch / MSC and the access technology can be based on IP / GSM / CDMA / CDMA2000 / UMTS / WCDMA.
Where the purpose of IP-PBX is …
For. Convert IP phone calls to TDM calls to interact with PSTN or other switches.
B. Switch calls within the IP-PBX phones
Below is a wide difference based on definition.
Soft switching …..
A programmable network switch that can process signaling for all kinds of packet protocols. Also known as “media gateway controller”, “call agent” or “call server”, these devices are used by operators that support converged communication services by integrating SS7 phone signaling with packet networks. Using network processors at their 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 native IP media gateway and / or endpoints,
(2) select processes that can be applied to a call,
(3) provide routing for a call within the network based on signaling and information from the customer database,
(4) transfer control of the call to another element of the network, and
(5) interface and support of management functions such as provisioning, fault, billing, etc.
The software makes it flexible …
The switching technology in a softswitch is in the 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 switchboard ….
(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 are also compatible with traditional analog and digital telephones, allowing businesses to slowly migrate to an all-IP telephony environment.
That is all. It seems complicated and confusing. It may be … but it doesn’t have to be.