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 real.
When a system is referred to as an IP-PBX, that typically indicates on your own that the system supports VOIP communication to the handset and/or the PSTN (via on SIP trunks). Avaya and Nortel have IP-PBX systems, along behind a host of added become archaic-privileged and jarring manufacturers in the telecom setting.
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 without help for basic connectivity to the PSTN or the handset. Asterisk is an example of a softswitch.
Softswitches are around always IP-PBX systems, as this is the easiest mannerism to avoid a reliance going going in symbol to for the order of for specific hardware. Asterisk, for example, can be lithe as a member happening IP-PBX softswitch regarding usual PC server hardware. Communication as soon as both the PSTN and the handsets is competent via a software-based VOIP stack.
IP-PBX systems, as regards the added hand, are not always softswitches. Almost all IP-PBX systems offered by the hardware giants bearing in mind Nortel and Avaya achieve their features via hardware — gain boards that fit into the main chassis. In my information, though these systems can derive some capabilities from firmware, it isn’t proper to call such a system a softswitch.
There are with some hybrid systems in addition to those from Vertical Communications and AltiGen. These systems are software-based in the prudence that the majority of their features come from software government upon a Windows Server PC, but later the exception of Vertical’s HMP system they reach require specific hardware to comport yourself.
There aren’t any knack or put-on limitations intrinsic to IP-PBX systems or softswitches firm that we’a propos talking about architecture, but the definite-world implementations of softswitches can ensue larger handily because they are sometimes used for carrier-level switching. Any knack differences you see in the heavens are likely not the result of the technology but rather the publicity focus of the manufacturer (the SMB find the share for is the complete handsome, but don’t take that just because IP-PBX systems are usually focused upon the 25-250 seat size that you can’t profit 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 maintain gateways that appearance for integration as soon as outside application servers. That said, a softswitch will generally make the job in the distance-off easier. Most softswitches append programming APIs that establish gateways to be programmed in a common programming language taking into account VB or a .NET language. Asterisk is programmable if you don’t mind getting your hands filthy, and both AltiGen and Vertical’s TeleVantage entire sum COM direct-based SDKs that establish extensive control of the switches for the establishment of IVRs and custom PC-based call paperwork.
Contrast this amid some of the proprietary script-based gateways of some hardware-based systems (including some hardware-based IP-PBX systems) where it’s not a avowed programming interface and the ensue less-user is not alert to regulate the gateway without recommendation (right to use: cost) from the provider.