In addition to the hardware, Private Branch Exchange systems need connectivity. There are a wide variety of options available, each with their own cost and performance advantages. The most basic connection is called an FXO or Foreign Exchange Office. That's another way to say analog telephone line to a phone company central office or CO. These are individual twisted pair connections that provide dial tone and local phone service. They may also be set up for long distance calling and toll free numbers. For one to a few lines, it's hard to beat good old analog lines for cost and voice quality.
Once your business has grown to the size where you are using more than a half-dozen outside lines, it's time to consider trunking services. A trunk is digital phone line that carries multiple conversations simultaneously. The most popular digital trunk line is ISDN PRI, which stands for Integrated Services Digital Network Primary Rate interface. That mouthful is jargon for a T1 line that offers up to 23 outside lines plus faster call switching and Caller ID. Another version of T1 telephone service offers 24 phone lines, but slower call switching and no Caller ID information. ISDN PRI lines usually plug into an interface card on your PBX system, a common option.
The reasons to go with ISDN PRI service are high voice quality at lower cost than multiple analog lines. This type of service is very popular with corporate users and call centers. Each line can be configured for incoming and/or outgoing calls. DID service can give each employee their own telephone number without having a separate outside line for every number. The system assigns lines as needed. Larger organizations can get multiple ISDN PRI lines for greater capacity.
The newest PBX systems go by the designation IP PBX. This is enterprise VoIP telephony. IP PBX systems can have individual lines run to each phone or use SIP handsets connected to an Ethernet network. SIP is the switching technology of VoIP. A SIP trunk can provide outside phone lines and even Internet service as an option to the combination of ISDN PRI trunking plus T1 dedicated Internet access.
With all these options, how do you go about choosing the right service for the performance and capacity you need? An easy way is to get free comparison pricing and discussion of your needs with a expert consultant from Telarus through the Shop For T1 service. Even if you already have a phone system that you are happy with, Telarus can likely save you money on your monthly business phone bills.