| IP-PBX systems and softswitches are in some ways | | | | AltiGen and Vertical's TeleVantage include COM |
| apples and oranges. While in most cases softswitches | | | | object-based SDKs that allow extensive control of |
| are IP-PBX systems, the reverse is not always true. | | | | the switches for the creation of IVRs and custom |
| When a system is referred to as an IP-PBX, that | | | | PC-based call management. |
| typically indicates only that the system supports | | | | Contrast this with some of the proprietary |
| VOIP communication to the handset and/or the | | | | script-based gateways of some hardware-based |
| PSTN (via something like SIP trunks). Avaya and | | | | systems (including some hardware-based IP-PBX |
| Nortel have IP-PBX systems, along with a host of | | | | systems) where it's not a standard programming |
| other established and new manufacturers in the | | | | interface and the end-user is not able to modify the |
| telecom space. | | | | gateway without assistance (read: cost) from the |
| A "softswitch" in the truest sense is a PBX that | | | | provider. |
| derives its feature functionality primarily from | | | | The major difference between Softswitch and |
| software. Voicemail, call handling, call center | | | | IP-PBX is that they are analogous to Switch/MSC and |
| functionality, etc., are all implemented via software | | | | PBX respectively in TDM networks. |
| and use hardware only for basic connectivity to the | | | | Only Softswitch can act as a Switch/MSC and the |
| PSTN or the handset. Asterisk is an example of a | | | | access technology can be based on IP/GSM/CDMA |
| softswitch. | | | | CDMA2000/UMTS/WCDMA. |
| Softswitches are almost always IP-PBX systems, as | | | | Where as IP-PBX purpose is to ....a. convert the IP |
| this is the easiest way to avoid a reliance on specific | | | | Phone calls to TDM calls to interface with PSTN |
| hardware. Asterisk, for example, can operate as a | | | | Switches or other switches.b. Switch calls within the |
| pure IP-PBX softswitch on standard PC server | | | | phones of IP-PBX |
| hardware. Communication with both the PSTN and | | | | A broad definition based difference is below. |
| the handsets is accomplished via a software-based | | | | Softswitch ..... |
| VOIP stack. | | | | A programmable network switch that can process |
| IP-PBX systems, on the other hand, are not always | | | | the signaling for all types of packet protocols. Also |
| softswitches. Almost all IP-PBX systems offered by | | | | known as a "media gateway controller," "call agent" |
| the hardware giants like Nortel and Avaya achieve | | | | or "call server," such devices are used by carriers |
| their features via hardware -- expansion boards that | | | | that support converged communications services by |
| fit into the main chassis. In my opinion, while these | | | | integrating SS7 telephone signaling with packet |
| systems can derive some capabilities from firmware, | | | | networks. Using network processors at its core, |
| it isn't proper to call such a system a softswitch. | | | | softswitches can support IP, DSL, ATM and frame |
| There are also some hybrid systems like those from | | | | relay in the same unit. |
| Vertical Communications and AltiGen. These systems | | | | According to the International Softswitch Consortium, |
| are software-based in the sense that the majority of | | | | a softswitch should be able to ..... |
| their features come from software running on a | | | | (1) control connection services for a media gateway |
| Windows Server PC, but with the exception of | | | | and/or native IP endpoints, |
| Vertical's HMP system they do require specific | | | | (2) select processes that can be applied to a call, |
| hardware to operate. | | | | (3) provide routing for a call within the network |
| There aren't any capacity or capability limitations | | | | based on signaling and customer database |
| intrinsic to IP-PBX systems or softswitches given | | | | information, |
| that we're talking about architecture, but the | | | | (4) transfer control of the call to another network |
| real-world implementations of softswitches can grow | | | | element, and |
| larger simply because they are sometimes used for | | | | (5) interface to and support management functions |
| carrier-level switching. Any capacity differences you | | | | such as provisioning, fault, billing, etc. |
| see in the market are likely not the result of the | | | | Software Makes It Flexible ..... |
| technology but rather the marketing focus of the | | | | The switching technology in a softswitch is in |
| manufacturer (the SMB market is very attractive, but | | | | software (hence its name) rather than in the |
| don't assume that just because IP-PBX systems are | | | | hardware as with traditional switching center |
| usually focused on the 25-250 seat size that you | | | | technology. This software programmability allows it to |
| can't get them larger). | | | | support existing and future IP telephony protocols |
| Connectivity to a third-party application server isn't | | | | (H.323, SIP, MEGACO, etc.). |
| something that would necessarily be impacted by the | | | | IP PBX .... |
| IP-PBX / softswitch distinction, as even most purely | | | | (Internet Protocol Private Branch eXchange) A |
| hardware-based systems these days support | | | | telephone switch that supports voice over IP (VoIP). |
| gateways that allow for integration with external | | | | IP PBXs convert IP phone calls into traditional |
| application servers. That said, a softswitch will | | | | circuit-switched TDM connections for the PSTN. They |
| generally make the job far easier. Most softswitches | | | | also support traditional analog and digital telephones, |
| include programming APIs that allow gateways to be | | | | allowing enterprises to migrate slowly to an all-IP |
| programmed in a common programming language like | | | | telephony environment. |
| VB or a .NET language. Asterisk is programmable if | | | | That's it. Looks complicated and confusing. Can |
| you don't mind getting your hands dirty, and both | | | | be....but doesn't have to be. |