Occasionally, you’ll see the word “convergence” come up in regards to phone systems.  But what does it mean?  In a word, flexibility.

Traditional, “old school” phone systems have always had two different types of ports: one type to support phone lines (dialtone), and another type to support the phones.  Since all phones used to be analog phones, this second port type would also handle fax machines, credit card machines, and cordless phones, all of which have analog interfaces.

Over time, phone system manufacturers realized that they could increase flexibility and features by making digital phones rather than analog ones.  Today, most phone system manufacturers who have been around for awhile offer digital phones.  Because each manufacturer has its own idea of what would make for the best features in a phone system, its own “killer apps”, and implementation of features, these digital phones are proprietary and cannot move from one phone system type to another.  Phone companies (dialtone providers), as well, realized that there were certain advantages to going digital, and began to offer digital phone lines.  By far the most common of these is a T1 line, which can carry up to 24 conversations simultaneously.  One flavor of T1 called ISDN/PRI is now the most popular due to it’s support of Caller ID (which a “plain” T1 does not support), and its enhanced signaling and troubleshooting capability (this is accomplished by having messages on the setup, progress, and teardown of calls take place on one of the 24 channels, leaving 23 available for voice conversations).  Most phone system manufacturers now support T1/PRI.

In the last few years, we’ve seen the emergence of VoIP (or IP) phone technology, which promises to offer certain advantages over regular digital phones.  The greatest of these is the ability to effortlessly move phones from one desk to another and keep the same extension, and the ability to use a phone off-premises and participate as if you were still in the office.  This last item is significant, as it gives businesses flexibility to allow remote workers the ability to handle office calls just as if they were there in person. (There are actually several “flavors” or different types of VoIP, which is treated in a separate post.)

Even with the marvelous capabilities that IP phones enable, digital phones are here to stay for the foreseeable future.  The reasons include, but are not necessarily limited to, IP phones being more expensive than their digital counterparts, and more potential for quality issues with VoIP.  Some manufacturers have decided to keep their digital phone systems and IP phones separate, meaning that if you decide digital phones are best for you now, but would like to have IP phones in the future, you’ll need to upgrade the whole phone system.  Other companies, typically ones who began life as data-driven companies such as Cisco, don’t offer digital (non-IP) phones.  They mask their lack of experience and R&D in this arena by claiming that IP phones are the best solution in every situation.

Other companies, such as ESI (whose phone systems we sell), have decided to take a converged approach, meaning that their phone systems will support either digital or IP phones equally well, in any combination.  If it makes sense for you to have digital phones inside the office (as we argue here is generally a good idea), and IP phones outside the office, you can do that.  If you’d only like digital phones now but would like to add IP phones later, you can do that as well.  In fact, ESI Communications Server phone systems support everything I’ve mentioned, including digital, IP or analog phones/devices, as well as analog lines or T1/PRI.  It’s a great day we live in, and flexibility is the name of the game.

Any new business, in the course of getting their new facility operational, must do a host of things to prepare to get themselves up and running.  One of these important things is to purchase a phone system, as this will be your primary means of communication with the world (if you’re like most businesses, anyway).  One of several choices that comes along with a new phone system is what type of dialtone you will order.  Choosing the right type of dialtone for your needs can save you headaches (and money) in the long run, and make your staff more productive.

The most common type of dialtone is the analog line.  This is known by several names: a BBL (”Basic Business Line”), 1FB (”1 Flat Business” line), or POTS line (”Plain Old Telephone Service”), among others.  It’s the same type of line that is commonly delivered to residences.  Normally, a business using analog lines will order several of them, each having its own telephone number.  Usually, most or all of these lines will be placed in a “hunt group” so that you can publish a single telephone number in the phone book, but allow multiple people to call you simultaneously (if the published phone number’s line is in use, other calls will “wrap” to the second line, third line, and so forth automatically).  A fax number is usually ordered as a separate analog line and not placed in the hunt group.

With analog lines, there are usually a number of features available to you via the dialtone provider (the company that delivers the lines and actually provides your dialtone service).  Features like call waiting, Caller ID, conference calling, and many more features are available as either part of the standard package offered by the provider, or via an additional monthly fee.  Some of these may also be available as features on the phone system itself (such as conferencing), in which case you may be able to save money by using them via your phone system rather than through your dialtone provider.  We have seen that in terms of ordering time, about two weeks is standard in the Phoenix area with most carriers.

Another type of dialtone available to businesses is a T-1.  A T-1 always features multiple lines, or channels, up to 24 for a full T-1 circuit.  Most providers offer the choice of a partial T-1 to those customers who do not need a full 24 lines (usually a T-1 is provisioned in 4, 8 or 12-channel increments).  Rather than being analog, a T-1 line is digital, which gives some advantages.  First, the quality tends to be better as you don’t get as much background “hiss” or static.  T-1 technology also allows for special phone numbers called DID, or Direct Inward Dial, numbers. These are numbers that, in conjunction with your phone system programming, allows for an outside caller to call directly to specific desks within the office.  In this manner, you can provide a direct phone number for as many of your employees as you wish.  Unlike with analog lines, where you will pay a set amount (say, $40 or so) for each phone number, with a T-1 you pay for the lines (talk paths) each month, and the phone numbers themselves are practically (but not quite) free.  This can be done because, unlike with analog lines, where each line must have its own phone number assigned to it, lines on a T-1 do not have specific phone numbers assigned to each line.  This actually makes a T-1 much more efficient in terms of being able to route calls.  As for other features, it should be noted that, unlike with an analog line where there are many features offered by the dialtone provider, most features on a T-1 are expected to be provided by your telephone system.

One special type of T-1 is called ISDN PRI (or just PRI for short).  This has all the advantages of a normal T-1, but unlike with a T-1, which does not offer Caller ID service, a PRI offers Caller ID.  With a PRI line, you can get a maximum of 23 calls occurring simultaneously, instead of 24, because the 24th channel is used as a data channel; it’s how your phone system communicates with your dialtone provider, and it carries information on the setup, progress and teardown of all calls taking place on the circuit.  This is extremely helpful at times for troubleshooting purposes.

One popular type of PRI is a Dynamic PRI, in which your phone lines and Internet are shared.  Your Internet has a base speed of about 1.5 Mbps, and for each voice line that is in use at a given time, your Internet will go slightly slower.  Lots of businesses like this type of PRI because it allows them to have a full PRI circuit and Internet for essentially the price of a PRI circuit alone.

Traditionally, T1/PRI has been something that smaller businesses could not afford.  This has changed a bit in the last few years, and now it is commonplace for even small businesses to have this type of circuit (especially now that Dynamic PRI is available in most markets).  If your business has 8 or 10 lines or more, you may find it cost-effective to go this route.  With any type of T-1 (or PRI), it normally takes longer to be delivered.  6 to 8 weeks seems to be standard turnaround time for ordering.

The last type of line that is common in the United States is a VOIP, or Voice Over IP line.  This is where calls, rather than being routed over a dedicated line from end to end, travel over an IP network (maybe even the Internet, depending upon who your provider is and their offering).  Without going into detail, VOIP technology allows dialtone providers to be much more efficient, and VOIP lines are becoming a very popular option both for dialtone providers and consumers.  For dialtone consumers, the monthly cost of VOIP lines is usually less than other options, both in the monthly base price and in long distance fees.  A possible downside to this type of line is that, with certain providers and depending on how the dialtone is delivered, you may have voice quality issues from time to time.  Many people also find that a fax machine, modem, or alarm line will not work reliably on a VOIP line.

Whether you decide to use analog phone lines, T-1 (or PRI), or VOIP phone lines, it is important that you purchase the type of interface from your phone vendor that supports the type of line you have chosen.  Dialtone providers offering VOIP lines recognize that this is fairly new technology, and that many residences and businesses do not have the type of phone equipment that will support VOIP lines directly.  For this reason, many, if not most, of them offer conversion boxes that “translate” VOIP into something that your home phone or business phone can understand; the conversion box makes it appear to your phone system that the line is an analog or a T-1/PRI line (this is, in fact, what a Dynamic PRI line is–VOIP lines that are converted so that they appear to your phone system as if they are a regular PRI).  If your phone system natively supports VOIP lines, no conversion box will be needed.  You should, in that case, communicate with your phone system vendor to ensure that the particular dialtone provider and service you are considering is supported by the equipment; this is because, while there are some common standards that are emerging, the particular “flavor” and implementation of VOIP offered by the various providers may be different.