(Ref: TrixBox without Tears - http://dumbme.voipeye.com.au/trixbox/trixbox_without_tears.htm )
(Ref: TrixBox Appliance - http://www.voip-info.org/wiki/view/Trixbox+Appliance+PBX+with+6FXO+%252B+2+FXS+Ports )
1. What do the terms FXS and FXO mean?
FXS and FXO are the name of ports used by Analog phone lines (also known as POTS - Plain Old Telephone Service).
FXS - Foreign eXchange Subscriber interface is the port that actually delivers the analog line to the subscriber. In other words it is the ‘plug on the wall’ that delivers a dialtone, battery current and ring voltage.
FXO - Foreign eXchange Office interface is the port that receives the analog line. It is the plug on the phone or fax machine, or the plug(s) on your analog phone system. It delivers an on-hook/off-hook indication (loop closure). Since the FXO port is attached to a device, such as a fax or phone, the device is often called the ‘FXO device’.
FXO and FXS are always paired, i.e similar to a male / female plug.
Without a PBX, a phone is connected directly to the FXS port provided by a telephone company.
If you have a PBX, then you connect the lines provided by the telephone company to the PBX and then the phones to the PBX. Therefore, the PBX must have both FXO ports (to connect to the FXS ports provided by the telephone company) and FXS ports (to connect the phone or fax devices to).
An FXO gateway
To connect analog phone lines to an IP phone system you need an FXO gateway. This allows you to connect the FXS port to the FXO port of the gateway, which then translates the analog phone line to a VOIP call.
An FXS adapter a.k.a. ATA adapter
An FXS adapter is used to connect an analog phone or fax machine to a VOIP phone system or to a VOIP provider. You need this because you need to connect the FXO port of the phone/fax machine to the adapter.
2. Analog Phones, IP Phones and Soft Phone for use with TrixBox
You can buy SIP phones from Grandstream, SNOM, and Cisco etc. Or you can buy an ATA (Analogue Telephone Adapter) produced by Linksys, Netcomm or Sipura, which enables you to use an analog phone.
You can use an IAX softphone called IDEFISK. You can get IDEFISK from here:
http://www.asteriskguru.com/tools/idefisk_beta.php. You can also use Virbiage softphone as it will handle IAX.
To get started, it is easiest to get a softphone and run it on another computer. See the section on installation of Softphone later in this document.
3. What cards are needed to interface with the PSTN lines
Based on the information provided for TrixBox appliance, if we want to connect a PSTN line (regular phone lin efrom Verizon or Vonage) to TrixBox, you need a card with 1 or more Phone (FXO) ports. To connect some 'analog phones' (typically Fax machines), you would need 1 or more Line (FXS) ports.
Some cards which support this, are
- NXA800P + 2 NXS100 + 2 NX0100 (https://www.nxtvox.com/cart/product_info.php?products_id=29)
- DGM-TDM822B (http://www.voiplink.com/Digium_TDM822B_p/digium-tdm822b.htm) - Recommended
- DGM-TDM22B (http://www.voipsupply.com/product_info.php?products_id=298)
4. Some common rules (rules of thumb) for small business VOID trunks
1.) 1-2 analog lines used for main point of inbound communication (rollover if more than 1)
2.) Cable or DSL provider (1.5mb down / 512kb up)
3.) Router capable of packet prioritization
4.) SIP DID with 2-4 channels
5.) Call forward on busy the analog lines to a DID on the SIP provider
5. IP Phone alternatives
Now, you could buy an IP phone and plug-in your Asterix system (more info later), or you could buy an FXS phone adapter (like Linksys SPA-2002 - http://www.voipsupply.com/product_info.php?products_id=713 ) and hook in a regular phone to the adapter.
6. IP Phones
Some IP phones, which in theory should 'simply connect to the IP, setup an IP address for the device, configure in TrixBox' and you should be good to go. Haven't done this yet - hence "in theory".
- NetComm V85 - http://www.netcomm.com.au/VoIP/V85_new.php
- Zultys zip4x5 - http://www.zultys.com/index.jsp?tab=productdetail&product=zip4x5&detail=datasheet-zip4x5&type=phones
- snom 320 - http://www.snom.com/en/snom320_voip_phone0.html
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