[Asterisk-Users] Semi-newbie question "Softswitch" and Asterisk - Is there a difference?

[Siggi Langauf]

Hi Bruce,

On Wed, 6 Aug 2003, Bruce Ferrell wrote:

[...]
> Is there a difference between what asterisk is and a softswitch?  Can
> someone explain it in small words and phrases for me?

Sure, there is. First of all, * is much cheaper.

But technically, * does much more than a soft switch:
AIUI, a classicals "soft switch" _only_ serves the purpose of managing
call setup for a group of terminal devices.
* is more like a classical PBX:
Terminal devices can actually connect to *. Asterisk can either simply
transfer calls to the correct location (much like a soft switch), but it
can also function as a (quite universal) telephony gateway (or "proxy").
Additionally, * provides advanced IVR scripting, Voicemail, call queueing,
and with some tweaking: a text-to-speech gateway, or even voice
recognition.

I guess you get the picture, but let's try to list asterisk's features
along with their "classical VoIP" pendant (AFAIK them) in brackets:

- manage call setup between end devices and gateways (soft switch)
- Convert VoIP calls to analog (or ISDN) lines (POTS or ISDN gateway)
- Connect otherwise incompatible VoIP devices, eg SIP<-->H.323
  (advanced soft switch)
- Convert incompatible audio codecs, eg GSM to G.711 (?)
- Provide outside access for an otherwise firewalled IP phone network
  (VoIP proxy)
- Voice Mail (voice mail system)
- IVR applications (IVR server)
- Music on hold source (?)
- ... (I'm quite sure I forgot something.)

As you can see, I'm not quite a specialist in classical telephony systems
(or maybe some of *'s functions just do not have a classical pendant), but
I guess you got an idea.

Cheers,
	Siggi