Voice Pri - Is It Right For My Business?

By Author: Steve Norris
Total Articles: 23
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For midsize businesses, a time will come when they will be asked about moving to a Voice PRI with their next service provider change or phone system change. How does a business decide if a Voice PRI is right for them? Let's take a look at some of the unique benefits of PRI, and what they can mean to your business.

Let's get technical for just a moment to define PRI:

The primary rate interface (PRI) is a telecommunications standard for carrying multiple DS0 voice and data transmissions between two physical locations. All data and voice channels are ISDN and operate at 64 kbit/s. North America and Japan use a T1 of 23 B channels and one D channel which corresponds to a T1 line. Europe, Australia and most of the rest of the world use the slightly higher capacity E1, which is composed of 30 B channels and one D channel. Fewer active B channels (also called user channels) can be used for a fractional T1. More channels can be used with more T1s, or with a fractional or full T3 or E3.

Each B-channel carries data, voice, and other services. The D-channel carries control and signaling information. The Primary ...
... Rate Interface consists of 23 B-channels and one 64 kbit/s D-channel using a T1 line or 30 B-channels and 1 D-channel using an E1 line. Thus, a Primary Rate Interface user on a T1 line can have up to 1.544 Mbit/s service or up to 2.048 Mbit/s service on an E1 line. PRI uses the Q.931 protocol over the D-channel. The B and D channel sizes are dependent on the Framing format of the T1 circuit. ie. Super Frame (SF) is a 56kb channel and the Extended Super Frame (ESF) is a 64kb channel. Nearly all US carriers provide PRI via ESF format and B8ZS line coding.

In English?

The Voice PRI is a high capacity communications line designed to give the business user more features at a more competitive price with greater flexibility. The service is carried via T-1 line, and gives the user calling capacity of 23 simultaneous calls for each T-1 PRI line. This service is practically a must now for any company with 20 users or more depending on call volume.

Are there costs associated with a PRI?

Yes. In order for your phone system to interface or talk to the PRI circuit from your T-1 carrier, your phone system must have a digital PRI card. Not all systems have the ability to handle a PRI card, but most do. PRI card prices can range anywhere from $500 to upwards of $3,000 depending on the age of the system and who the manufacturer is. Add installation costs, and it's a decision that is carefully weighed against the benefits.

What are the benefits of a PRI?

In comparison to an analog environment, the benefits of a PRI are many. Hunting groups, DID's, call tracking and call reporting, CTI, out of rate center DID's, pulsed digits, call routing, less taxes and reduced costs are all chief reasons to consider Voice PRI.

1. Hunt Groups: In an analog environment, it is typical to have a linear or circular hunt group for all incoming calls, and possibly for outgoing calls. All incoming calls start from the top of the hunt group and work their way down to the bottom. A ten (10) phone line hunt group would allow an organization to have 10 simultaneous incoming calls with a single main number. Outgoing calls would then pick up the last of the ten (10) lines in the hunt group and work their way up towards the main or first line in the hunt group. The goal obviously is to have a large enough hunt group so that the incoming calls and outgoing calls never cause you to use all of your capacity. This is called line pooling in an analog environment.

If you have multiple businesses or departments, you will often have separate line pooling hunt groups. Changes in configuration and capacity have to be made through your carrier. Private lines are typically left off the hunt groups at additional costs. With a PRI, you can have multiple hunt groups all programmed from your phone system. Your basic rule is that you can make or receive a total of 23 simultaneous calls in whatever configuration you want per PRI, and they can be bonded. Do you want 10 different hunt groups for 10 different departments? No problem. Need a dozen private numbers? No problem. You don't even have to call the carrier, as the programming is done at the PBX level.

2. DID's: Direct Inward Dial numbers are key for any growing organization. Direct Inward Dial numbers are typically assigned in blocks of 20, and are designed exclusively to work with digital voice circuits like PRI. Most carriers limit the number of DID's per PRI circuit to 200, but we've seen some rare cases where 400-600 have been allowed. Did you catch that?

I have 23 channels on a PRI for simultaneous phone calls, but you can give me 200 phone numbers?

Yes, that's right. You literally can assign everyone in your organization their own phone number AND their own fax number if you want. Phone numbers run around $5 a month per block of 20.

Why would I want all those numbers?

Do you consider service a priority? Then perhaps you insist on your clients not having to deal with automated attendants. With DID numbers, your incoming caller can bypass the automated attendant and have their call routed directly to your representative of choice. In a world of automation, large companies wouldn't do without it. Is your receptionist inundated with calls and a professional call transferer? Bypass the need by routing the call directly to their party.

With the ever increasing capabilities of desktop fax server applications, it is also possible for every employee to have their own fax number that delivers .pdf or other common format attachments to their desktop via email application. Send and receive faxes from the desktop without getting up, and without paying for additional dedicated fax phone lines.

3. Call Tracking and Call Reporting: Along with DID's, the enhanced capabilities of your phone system to track your data with a PRI can be vital to your operation. (Software often required) Ever wonder just how many outgoing calls your sales reps are making? Need to know how many incoming calls came in to customer service to assist with staffing decisions? How many calls did you get on that last advertising campaign? With DID level call tracking and reporting, you can create a myriad of tools for your business to streamline operations like never before.

4. Out of Rate Center DID's: Some areas call them exchange numbers, foreign exchange numbers, Remote Call Forward numbers, etc. Essentially they are numbers in neighboring markets outside of your local phone company office that are forwarded to your location. The local phone company will often charge a monthly line charge in addition to any call volume charges and mileage charges associated with the number. Those costs can be astronomical for businesses that need a local presence in other markets. Locals in a market prefer to deal with someone who is also local, so having that local number is essential. With a PRI, you can turn your out of area number into a DID and avoid mileage and forwarding charges. For the right company, this can mean a difference of hundreds or thousands per year. It also opens up the ability to go after additional markets and have that local presence.

For companies that relocate, their local phone company will often tell them they cannot take their number with them. By using a CLEC, it is often possible to take your number with you to another market and not incur the high costs formally associated with doing so by forwarding or telebranching. .

5. CTI (Computer Telephony Integration): Many sophisticated business operations integrate their voice and data infrastructures, and they require the ability to route calls based on database lookups. Using DID's and the Caller ID of the incoming caller, your system via PRI can actually look up in your database which one of your representatives has been dealing with this customer, and route the call directly to their extension in a moment's notice. The user than can see a screen popup on their computer informing them of the status of this customer or account before they even answer the phone! This feature has limitless applications, but you must first determine if the protocol between your database and phone system is compatible. Common protocols are TAPI, TAPI 2.x, TAPI 3.x, H.323, and others.

6. Outgoing Caller ID: In large corporations or organizations with several companies under one roof, it is imperative to have separate outgoing Caller ID appearances. With PRI, you can assign an individual company name and number pulsed out by phone or phone group level, all while leveraging the same telecommunications PRI circuit.

Do you want all calls to go through the switchboard? Then assign the same Caller ID to all phones as the main outgoing Caller ID for your company. All callers returning calls will have the calls routed as you program. With PRI, you maintain total control, and can make programming changes as often as needed or desired. (Programming typically must be performed by a trained technician)

7. Reduced Cost: Growing businesses choose Voice PRI for all of the above reasons, but perhaps most importantly for cost reasons. If you have been operating in a similar capacity analog environment, but without the benefit of all of the above features, your scenario would look something like this:

23 analog lines monthly charge each: $30 (23 x $30 = $690)

Service Line charges per line: $6 (23 x $6 = $138)

Features charges: ??? Caller ID is often extra, but comes with PRI

Additional taxes: ??? Depends on carrier and Bell region

Calling charges: ??? Depends on carrier, region, and negotiated rates

$690 for 23 analog lines

$138 for service line charges

$828 before features, taxes, and calling charges.

Most T-1 carriers we deal with now offer PRI for around $500 a month plus a line charge equal to 5 channels of the PRI. (Around $30) PRI has Caller ID included automatically, although some carriers charge an additional fee for Caller ID Name and Number. So for $530 per month, you get all of the above mentioned features, typically more competitive calling rates, reduced taxes and line charges, and a bottom line difference of around $300 per month. So..

When should I move my business to a Voice PRI?

When it costs less to be digital over analog, or whenever the benefits of the additional features outweigh any additional costs associated with the service. Additional options are now available with fractional PRI circuits, integrated voice and data PRI circuits, and voice compression high capacity options that have made the service affordable for most businesses. Your telecommunications professional can help you decide which option is right for you.