Can anybody explain why open-source Asterisk is favourable in comparison with a traditional PBX system from a vendor such as NEC/Syntel/Matrix or Siemens.
Being in a position currently where the powers that be bought a Panasonic PBX.
There's a bunch of features that aren't there (or rather, are individually licensed). Such as MeetMe (conference calling), or hot-desking.
There's also the problem that all the phones are effectively hard-wired to their ports. They had to run new cables for the phones, instead of using our structured cabling. They have to come in every time we want to move a phone, or change a name, and refuse to do a handover and give us the access software and magic runes for the hardware. It's also more expensive. There's vendor lock-in associated with the hardware, and the phone handsets, and the conference phones, whereas with Asterisk, you can use any phone that supports SIP. Oh, and the vendor's phones don't support SIP generally, so once you've got them, switching to Asterisk isn't cost effective.
Choose Asterisk. Or better, Freeswitch. Seriously. You can do things with Asterisk that are impossible/difficult/expensive to do with a traditional PBX. There are even Asterisk appliances (and virtual appliances) available that will give you a plug-and-play experience and a web-based configurator.
In 2012, there is no reason to choose a vendor-specific hardware PBX. Really. No reason at all.
I would separate your question into 2 areas:
- Going VoIP
- Going Open Source
Regarding the first one, I believe there is not much dispute, being VoIP extremely more powerful than traditional PBX, but to name a few:
- Usage of same network infrastructure you already have laying around, reducing cost
- Ability to connect remote endpoints without expensive point-to-point network infrastructure or tunnels
- Usage of soft phones (software) instead of hardphones only. Very useful in callcenter enviroments or road warriors
You will find more reasons applying to your enviroment at Wikipedia VoIP
Once you have established you will go VoIP, you have a basically 2 options: propietary or open source implementation/platform. Both share the same VoIP features, but by going open source you also gain:
- Independence: you will be able to use any endpoint terminal you choose to, as long as it supports your VoIP protocol (usually SIP). There are hundreds of vendors for SIP terminals, some of them orders of magnitude more cheaper that proprietary options
- Interconnect: you will be able to connect to any carrier that supports SIP, including for example Skype
- No licence fee: all features included, as long as your hardware supports it. Proprietary options tend to licence their features heavily and they are not cheap. This includes adding the ability to connect to an additional carrier, add some extensions or callcenter positions
- Freedom: open source allows you to change the code or hire someone else to do it for you in order to accomodate your requierements
- Community: software evolves. So will your platform.
Asterisk as an open source VoIP platform is very good, been working with it for more than 7 years now, but it has a learning curve. If you want to avoid this, you can go with Asterisk embedded appliances (like Digiums Switchvox) or you can use one of the several asterisk-centred distros like Elastix). There are also several commercial offerings that use Asterisk internally, so you gain the turnkey approach of proprietary offerings without losing your freedom.
You can find more info on the Asterisk project at http://asterisk.org/