The OfficeIPLink™ PBX can handle a wide variety of Carrier Interfaces which include

• PSTN
• VoDSL
• PRI (Primary Rate Interface) ISDN also known as an E1 in Australia and European countries and generally a T1 in the U.S.
• BRI (Basic Rate Interface) ISDN
• VoIP
• And several others which include interfacing to external Interface units.

The OfficeIPLink™ PBX, however, is not limited to one of these. You can mix and match these as per your business requirements and possibly budgets. Now many of you may not be aware of what each of these are, hopefully the descriptions below will provide a clearer idea as well as some of the reasons why you might use them.

PSTN

Generally, anyone that has had a phone at home or work, has come across the humble PSTN line. It is a single line, usually with a single phone number (although you can obtain a second number attached to it with some services), but essentially it is one phone number per line. The OfficeIPLink PBX can take almost any number of these lines whether it be two, four, eight, twenty-four, forty-eight, or any number in between these numbers. However in reality, any business using 6-7 PSTN lines would consider using ISDN/E1/PRI due to similar costs in relation to line rental, and the many more additional features that ISDN/E1/PRI can provide.

VoDSL

Very similar to PSTN lines, in fact the lines provided are electrically similar to PSTN lines. The main difference is that they are delivered digitally up to your premises. This means that telephone line fault monitoring and correction is vastly improved over the standard PSTN lines. The service is normally supplied in conjunction with an SHDSL Service (basically a real business grade Internet service). Whilst these lines are a higher cost than conventional PSTN lines, usually bundled with an SHDSL service, the cost is comparable and quite financially feasible for even a small business (5-10 users).

Another advantage of the VoDSL PSTN lines, is that it only requires one pair of copper wires into the premises. If you have ever been told that your building does not have enough copper pairs, this is a perfect solution, allowing you to have up to 8 PSTN lines off the one copper pair.

PRI/E1/ISDN

Many businesses have not been introduced to the ISDN/E1/PRI service however others may have come across it when it was branded as OnRamp 10/20/30 from Telstra. This was historically due to the large installation costs. Voiceintegrity can organise free installation of an ISDN/E1/PRI service with a minimum 2 year contract. The names PRI, or E1, or ISDN are quite often used interchangeably as descriptions of the service. However as ISDN was a term that described the one product from Telstra, we will move forward and describe this line purely as a PRI/E1 service

PRI/E1 is a digital service, right through to the PBX. Like the previous category, it is monitored and again faults in many cases are identified before you may become aware of them.

Normally PRI/E1 comes as a 10 channel, 20 channel or 30 Channel service. In other words if you need 12 lines, you will need to go to 20 channels. There are some carriers who can provide channel by channel after 10 lines, but it is more of a hybrid solution and generally the carrier costs are higher, especially for the calls. You will note that we now call them channels as that one line to one number relationship is no longer in existence. In fact when you take the PRI/E1, you also get assigned a 100 range of phone numbers. This means anyone that calls any one of these numbers will come into your PBX. The only limitation is that you can only take 10 calls concurrently (if you have taken the 10 channel option). What this also means is that 10 calls can call the same number on the PRI/E1 service and they will not get an engaged tone (unless you point them to one extension). You might say that my PSTN service can do that now, but it is actually done by a method called Line Hunt which goes from line to line looking for line not being used.

The OfficeIPLink™ PBX on PRI/E1 lines can determine the number that was called as it is passed this information bu the PRI/E1 line. This is important, especially if you have certain called numbers going to different extensions or groups within the business.

We find more and more businesses are finding ISDN as a suitable product for their business, especially for growing businesses. Even if you start with 10 channels, the OfficeIPLink™ PBX interface supports up to 30 channels without additional hardware or additional licences, and this usually includes the carriers equipment as well. If you order an upgrade to your line, in most cases it is done online, relative quickly and painlessly.

Need more than 100 In-dial numbers. That's fine, for a small cost per month, you can obtain another block of 100 Numbers.

BRI/ISDN

Very similar in design and features as the PRI Product, except that it only comes as two channels. If you want 8 channels, you order four of these lines. Like the PRI/E1 connection they can take additional In-dial numbers, they are a digital line and as such is capable of being monitored.

However, with many of the other products out there, the BRI Interface is becoming less and less suitable for many businesses. This is recognised by the much higher costs of equipment and interfaces supporting the BRI interface. Many businesses who already have BRI connections have continued with BRI, mainly due to the change over costs, usually because the older PBX systems came with the BRI interface installed, and have found either parts not available for changing, or the licence costs prohibitive.

We generally will inform the client that it is a perfect opportunity to upgrade from the BRI service, especially at the time they implement the OfficeIPLink™ PBX.

VoIP (Voice Over Internet Protocol)

Now we come to VoIP connections. The OfficeIPLink™ PBX is extremely adept to working with VoIP connections. Companies that provide VoIP connections are actually called VSP (Voice Service Provider), and are rightfully called carriers as well.

Your normally select a VSP, sign up, and they organise for telephone numbers (known as DID's) to be attached to your account. The VSP will then provide you with a login/password combination which is entered on your OfficeIPLink™ PBX. When a caller calls one of your DID's, this call is then passed from the VSP to your PBX, and you take the call as normal like you would with a standard carrier phone call.

Many of the features of a VoIP connections are very similar to an ISDN line. Features of a VoIP Connection are follows

• Can have multiple DID's assigned to your account, which do not necessarily have to make the number of concurrent channels you have
• You can subscribe to have one channel added at a time, you do not have to take 10 Channels at a time.
• You can have just one DID or you can generally have as many as you need. Again you do not have to have 100 Indial numbers.
• Your VSP may have automatic Divert functions available. If your PBX is offline, your calls can automatically divert to another number
• Your DID numbers do not necessarily have to be at location your PBX is at. For instance you can arrange for a Melbourne Number, a Brisbane number and many more city and regional locations, providing your clients with a local number to dial.

Some of the limitations of VoIP, you must be made aware of are as follows:

• The number of channels you can achieve is limited by your Internet Bandwidth at your location
• If you share your Internet for other purposes, e.g. browsing, downloading, it can have a serious impact on call quality
• If you lose your Internet connection, you loose your capability to receive calls
• Depending on the VSP, you do not necessarily own those phone numbers. They remain the property of the VSP. You close the service, you lose the numbers.
• Internet quality varies from location to location. Just the fact that you can browse and your Internet connection is fast is definitely no guarantee that your Internet connection is VoIP Quality.
• You need to have an Internet line that is low contention and many ADSL connections do not fit this criteria.

VoIP has limitations as described. Many of these can be overcome by very good planning, selection of Internet carrier, and good fail-over measures, and in many cases, some of the features that VoIP offers, are very hard to look past, especially as they may not be able to be achieved by other means. We have a wealth of experience in this area and we are very pleased to discuss this area, including combining VoIP with standard carrier lines should you want to use VoIP with your OfficeIPLink™ PBX.