Showing posts with label PBX telephone systems. Show all posts
Showing posts with label PBX telephone systems. Show all posts

Sunday, October 16, 2011

Who Still Needs a T1?

With all the hoopla over copper and fiber Ethernet, plus new options in Cable broadband, that stalwart of business connectivity, the T1 line, is getting little fanfare these days. Does that mean that T1 is on its last legs? Or, is there a future for this proven telecom service?

T1 lines are available almost everywhere in the USA...Far from fading out, T1 is as popular as ever. New installations are being provisioned as you read this. The fact that T1 has been around for decades is one of its strongest features. That and the decline of T1 prices in tandem with competing Ethernet over Copper services are keeping T1 in the game.

So, who really needs T1? You do if you need professional grade dedicated bandwidth, secure point to point connections, or robust telephone trunking. That’s especially true if your business location is a bit off the beaten track. If you can’t get any wireline service other than plain old telephone, you probably can get a T1 line installed.

T1 has almost universal connectivity today. To understand how that can be when DSL and Cable rarely go past the city limits and Ethernet services are mostly found in business districts, we have to look back at why T1 was developed in the first place. We think of T1 lines as wide area network connections today, but in the beginning T1 was a telephone trunking system.

Prior to WWII, telephone companies connected to each other through analog lines on telephone poles or underground cables. Carrier telephony used a frequency division multiplexing scheme to load multiple conversations onto a single pair. In the 1950’s, Bell Labs developed digital multiplexing to replace the analog systems. The basic digital trunk was defined in the T-Carrier specifications. T-Carrier includes T1 and T3 lines.

The genius behind the design of T1 is that it runs on two pair of ordinary twisted pair copper. This is the subscriber loop connection that is installed in every business for telephone service. The wires are the same, but the signals on a T1 line are digital, not analog. While one copper pair can carry one business phone line, two copper pair can carry 24 phone lines or a digital bandwidth connection of 1.5 Mbps.

Another smart thing about the design of T1 is that provisions were made to boost the signal so that it can connect far flung locations. Not every business location is within a few thousand feet of a telco central office. Even analog signals fade out with distance. The much higher digital signal frequencies fade out much quicker. That’s why DSL is hard to come by. Unless you are close to the phone company CO, the DSL signal has little bandwidth capability left by the time it gets to your place.

The T1 support system was designed with a device called a regenerative repeater that can be installed in the line every mile or so to complete regenerate the signal. The noisy and faded input signal is boosted and reshaped so that at the output it looks like what comes out of the central office. Keep adding these repeaters and you can extend T1 service far out into the countryside.

If you have a business on the edge of town or in a remote location, you may still be able to get a T1 line for a reasonable price. The only real competition is two way satellite broadband. It works, but has very long latency times that make telephone service perform poorly, is subject to rain and snow outages, and has download limitations. If you exceed your quota, your speed will be reduced so that you don’t hog the limited resources of the satellite.

T1 has none of those problems. You get a rock solid 1.5 Mbps in both the upload and download direction. Load it full up with data transfers 24/7 or use what you need, the price is the same. Latency is negligible for most applications. In fact, T1 works great as a multi-telephone service or in the ISDN PRI configuration that supports most PBX telephone systems. You don’t have to get an Internet only data connections. T1 lines can be ordered between two business locations for a private line connection.

Is T1 the right service for your needs? Check T1 prices and availability instantly and compare with other options... if there are any that are suitable.

Click to check pricing and features or get support from a Telarus product specialist.




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Wednesday, January 12, 2011

SIP Trunks vs ISDN PRI

Enterprise telephony long ago advanced beyond analog business lines in favor of PBX telephone systems and ISDN PRI trunking. Now there’s another option that may offer cost and performance advantages for companies that want to improve their voice services. It’s called SIP Trunking. Let’s compare and contrast SIP Trunks with ISDN PRI to see how to choose between them.

Get availability and pricing on both ISDN PRI and SIP Trunking to see which is best for your company. Click for pricing.You should know that we are still talking exclusively about digital telephony. There is no analog transport in either a SIP Trunk or PRI. What differentiates the two is that ISDN PRI is based on a switched circuit model and SIP Trunking is based on packet switching.

For many companies it could be six of one and a half-dozen of the other. That’s because either trunking service can be made to work with your in-house phone system. The idea behind digital trunking is to carry a half-dozen or more outside phone lines on a single digital line. Usually that’s one or more T1 lines, although DS3, OC3 fiber or Ethernet can also be used.

ISDN PRI uses a T1 line configured into 23 separate voice channels plus one data and control channel. Most PBX systems and the newer IP PBX phone systems make it easy to connect to ISDN PRI. They either offer one or more PRI ports built-in or accommodate a plug-in adaptor card.

If you need more than 23 lines, you simply add more ISDN PRI lines incrementally. Each additional line can bring in up to 23 more business phone lines. You’ll have to check what’s available for your phone system, but it is not uncommon to have 2 to 4 PRI lines plugged into a PBX system.

The technology used for ISDN PRI is defined by the Integrated Systems Digital Network specification. PRI is the Primary Rate Interface. There is also a lower performance BRI or Basic Rate Interface that isn’t seen much anymore. This is a legacy telephone technology designed to support the idea of separate digitized telephone lines, one per channel. There’s no chance of interference between calls because the channels are strictly defined and timed using Time Division Multiplexing.

SIP Trunking is more of a network than a telephone based technology. It is a packet switched network line, much like you would use to connect two business locations. What SIP Trunking can do is directly support a converged voice and data network. You can run SIP Trunks between business locations to expand your voice and data network geographically.

The SIP in SIP Trunking stands for Session Initiation Protocol. That’s the switching technology used in VoIP telephone systems. In SIP trunking the control signals for the phone system are transported in packets that travel down the same network pipe as the voice packets.

ISDN PRI isn’t so much about convergence. It’s really about having separate telephone and data lines leave the premises, although you are free to converge your in-house network and let an IP PBX system on the network handle call routing, including outside calls on the ISDN PRI trunk line.

SIP Trunking doesn’t have to be about convergence, either. You can simply use a SIP Trunk to connect your PBX system to a telephone service provider rather than using an ISDN PRI. Depending on which CODEC or coding scheme you use, you may be able to handle more than 23 lines on a SIP Trunk. If you are using an Ethernet connection to your provider, you may be able to support dozens of phone lines depending on the bandwidth available.

For small businesses, SIP Trunks can be configured to transport both voice and data to your service provider. Most often this is used to bring in telephone lines and broadband Internet service on the same SIP Trunk. There’s a cost advantage, even if you are not running a converged voice and data in-house.

Since either ISDN PRI or SIP Trunking might be able to support your needs, how do you choose? That depends on the features you desire and what’s available to serve your particular business location. You may have several options to choose from. To find out, check out SIP Trunks and ISDN PRI availability and pricing now.

Click to check pricing and features or get support from a Telarus product specialist.




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