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VoIP PBX Interface Selection Guide (Asterisk Hardware)

Because voice over IP is digital, often a standard PC or server is used for the PBX. Those VoIP PBX's (aka IP PBX) need PCI interface cards to connect to analog telephone lines, digital T1/E1 lines, analog telephone handsets and fax machines. This category contains PCI interface cards from the leading manufacturers in the industry. If you are using Asterisk IP PBX or a variant such as trixbox, Elastix, AsteriskNOW, FreePBX and need to connect it to something, we are here to help. For our complete IP PBX Interface Buying Guide please browse to the bottom of this page.

Sangoma, Digium, Rhino, OpenVox, Redfone, Xorcom, Dialogic

Sangoma Connectivity Hardware Digium Analog & Digital Interfaces
Sangoma interface cards allow you to connect voice over IP PBX's to T1/E1services, analog telephone lines, analog telephones and fax machines. Sangoma offers optional hardware echo cancellation on most of their cards and all cards carry a Lifetime Manufacturer Warranty.

Digium, the creators of the Asterisk IP PBX software offer their own line of interface cards to connect your IP PBX's to T1/E1services, analog telephone lines, analog telephones and fax machines. Optional hardware echo cancellation is available on some of their cards.

Rhino Equipment OpenVox Cards
Rhino's high quality - made in America interface cards allow you to connect your IP PBX to T1/E1 services, analog telephone lines, analog telephones and fax machines Optional hardware echo cancellation is available of many of their cards.

 
OpenVox has a wide selection of budget-conscious interface cards with FXS/FXO ports and T1 / E1 ports for most IP PBX's. Connect your IP PBX to analog telephones, fax machines and analog telephone lines. OpenVox's A400M series is a great option for small, low power IP PBX's.

 
Redfone T1/E1 HA Interfaces Xorcom USB Asterisk Channel Banks
RedFone's solid state T1/E1 interface adapters are designed to provide high availability solutions for trixbox/Asterisk based solutions.

 
Xorcom's innovative channels banks deliver FXO, FXS, T1/E1 connections to your IP PBX system over USB 2.0 eliminating the need for available PCI slots.

Dialogic / Eicon Diva Cards

Dialogic offers a range of enterprise grade telephony interface cards designed specifically for large scale implementations and high reliability systems.

Telephone Circuit Interface Buying Guide

Telephone circuit interface cards are used to connect regular PC's and servers to analog and VoIP (digital) telecommunication equipment. Typically, this is done by inserting a PCI card (while the system is turned off) into a computer and installing any required drivers or software. The installation and configuration of these PCI cards should be performed by an experienced technician. Voiplink has sold thousands of PCI cards over the years, and our expereinced technical sales staff can assist you should you have questions.

To determine what specific PCI card you need, you need to know three things about your existing equipment. First, you need to know what types of circuits you are connecting to. You will also need to decide if you need to have hardware echo cancellation on the card. You will also need to know what PCI interface slots you have available on the motherboard of your computer. This will determine what type of interface you will need on the card.

1) What are you connecting to:

How many analog telephone lines do you have?
 - This is how many FXO ports you need

How many analog telephones & fax machines do you have?
 - This is how many FXS ports you need

How many T1/E1 circuits do you have?
 - This is how many T1/E1 ports you need

Remember to plan for growth!

2) Do you need echo cancellation:
If this is your first time installing a PCI card on the line it will be hard to predict whether or not you will experience echo. There are software tuning techniques to remove echo from the line but they consume system resources and are often inadequate.

Some manufacturers like Digium allow you to add the echo cancellation module to the card after you purchase it. This is beneficial because you can save some money up front (no hardware echo cancellation module) and upgrade later if you find you have echo on the line. Cards from most other manufacturers either include hardware echo cancellation or they do not, and it cannot be added later. I always use and recommend hardware echo cancellation, it's just one less thing to worry about. If I'm installing a system for a client, its not worth the damage to our reputation or the truck roll if echo pops up.


3) What type of motherboard interface do you need:
Next you need to determine what type of PCI interface your computer has available. At the time of writing, Voiplink sells 3 types of interfaces:
  • Standard PCI (older but, most common)
  • PCI Express (newer, faster, but less common)
  • MiniPCI (newest, specialized, but less common)
time of writing Dec '08

Standard PCI has been around forever and it's in almost every motherboard today. It is usually slightly cheaper than PCI Express (although Sangoma leveled their prices in late '08). I recommend Standard PCI because it's usually cheaper and people will most likely have this interface in their computer. That being said, eventually PCI Express will replace Standard PCI and the tables will be turned. PCI Express is faster and some people claim that VoIP benefits from the speed increase. I am a bit skeptical but I have never seen any evidence either proving or discounting this claim.

MiniPCI is a bit of a new comer to the VoIP industry. OpenVox released their A400M series MiniPCI cards earlier this year. The interface is found on small form factor systems and solid state appliances. MiniPCI is excellent for small, low power that just need basic features.

Finally, I will discuss the various PCI card manufacturers that we offer.


Sangoma Technologies
Sangoma interface cards allow you to connect voice over IP PBX's to T1/E1services, analog telephone lines, analog telephones and fax machines. Sangoma offers optional hardware echo cancellation on most of their cards and they are available in Standard PCI and PCI Express. Sangoma is well known for their innovative AFT architecture that requires only a single PCI or PCI Express slot yet can scale to 24 ports. Sharing the PCI interface ensures common synchronous clocking for all channels. Sangoma's  compact form factor can fit large port densities in almost any standard sized ATX case, something their competition can have a problem doing.  Sangoma's A series card
carry the industry's first and only Lifetime Manufacturer Warranty.*

*To qualify for Lifetime Warranty protection, the product must have been purchased from an Empowered by Sangoma partner, and the product must be registered by the end user at http://sangoma.com/warranty/register/

Voiplink is an Empowered by Sangoma partner.


Digium
The creator and primary developer of Asterisk IP PBX software, Digium offers a complete line of interface cards to connect your IP PBX's to T1/E1services, analog telephone lines, analog telephones and fax machines. Optional hardware echo cancellation is available on most of their cards. Digium offers both Standard PCI, & PCI Express interfaces. Digium solutions reduce the costs of traditional TDM and VoIP implementations through Open Source, standards-based software and next-generation gateways, media servers, and application servers. Digium was founded in 1999 by Mark Spencer whose mission is to transform the way businesses acquire and operate their communications systems through the application of open source software.

Rhino Equipment
Rhino's high quality - made in America interface cards allow you to connect your IP PBX to T1/E1 services, analog telephone lines, analog telephones and fax machines Optional hardware echo cancellation is available of many of their cards. Rhino offers PCI cards in both Standard PCI and PCI Express. They also offer a popular line of channel banks to provide FXS/FXO, T1/E1 connectivity.

Openvox
Has a wide selection of budget-conscious interface cards with FXS/FXO ports and T1 / E1 ports for most IP PBX's. Connect your IP PBX to analog telephones, fax machines and analog telephone lines. A few of Openvox's cards have hardware echo cancellation and they offer Standard PCI, PCI Express & MiniPCI motherboard interfaces.

RedFone
Manufacturers a line of T1/E1 hardware that is designed to provide immediate failover capabilities. The RedFone devices can detect a failure of the digital circuit and reroute calls to another circuit almost instantaneously.

Xorcom
Unique USB-based channel banks offer an affordable and flexible solution for expanding an IP PBX system with more FXO or FXS ports. While unconventional, the Xorcom Astribank products are ideal for high density analog ports and have the advantage of being able to work with even the smallest appliance systems so long as there is an available USB port.


Common Terms:

Asterisk is the most popular open source IP PBX in the world. Many variations of Asterisk are now available such as trixbox, AsteriskNOW, and elastix that can provide advantages and disadvantages over the original Asterisk. These IP PBX's can be loaded on to personal computers or business servers to build a feature rich, business grade voice over IP phone system.

There are four main types of interfaces on an IP PBX, FXS, FXO, T1/E1 and Ethernet. An FXS interface is used to connect analog telephones or faxes to the IP PBX. An FXO interface is used to connect analog telephone lines to the IP PBX. A T1/E1 interface is  used to connect the IP PBX to high speed, ultra-reliable internet connections. Ethernet interfaces are used to connect an IP PBX to the local area network (LAN).

T1/E1
Highly reliable digital data connection. Some VoIP providers can install a T1/E1 circuit to deliver phone calls to your IP PBX system. T1 is the US standard and E1 is the European standard. If you have a VoIP connection delivered over a T1, you do not need any telephone circuit interface equipment.

PRI (Primary Rate Interface)
A PRI is a telephony circuit that is delivered over a T1/E1 circuit, this is
the industry standard for delivering voice phone calls to business customers. Over a T1 you will get 24 simultaneous calls and an E1 will get you 30 simultaneous calls. You will need a T1/E1 interface card to use these types of circuits.

FXO: Analog telephone line connection (POTS) - 1 call per port - An FXO connection connects to an analog telephone line jack.

FXS: Analog telephone or fax machine connection - 1 device per port