17.3. Home/office phone system

17.3. Home/office phone system
	Chapter 17. VoIP

The FB2500 can be used as an office phone system (PABX) which allows you to connect a number of handsets (telephones) in your office, and make and receive calls from the telephone number using a subscription to a carrier over the Internet.

Traditionally a PABX would connect to one or more telephone lines, whether analogue or ISDN, and to a number of telephone handsets. The PABX would allow internal calls (handset to handset) and external calls to and from the external phone lines. It would have features like busy lamp fields and hunt groups.

The FB2500 does the same job as a traditional PABX, but using IP.

Instead of phone lines or ISDN, the external calls are handled via an Internet Provider (ISP) and a VoIP carrier. This can allow many calls and phone numbers to be used, and is generally a lot more scalable and flexible than traditional phone lines.
Instead of internal phone wiring to connect telephone handsets, the FB2500 connects to handsets via the office LAN network. This can be the same network as used for PCs, or separate, or segregated using VLANs.
Instead of analogue phones, or special system phones for a PABX, the FB2500 works with any standard SIP VoIP phones. There is a wide selection of phones available in a range of price brackets. The FireBrick has been tested well with SNOM phones, including features such as busy lamp field lights and buttons.
The FB2500 scales well to support hundreds of phones in an office without needing extra FireBrick hardware. This makes the FireBrick a much more scaleable and economical PABX solution than traditional systems.
It is possible to configure remote handsets, e.g. for home workers, connecting over the Internet.

The FB2500 can work with trunk carriers where one login/connection is used to carry many calls to different numbers, or it can appear to the carrier(s) as multiple separate VoIP devices, or any combination. This allows the FB2500 to be used with almost any VoIP carrier.


17.2. Registration and Proxies		17.4. Network Address Translation