ISDN 2 vs Broadband

[Chri5]

In the old days phones had exchange line service, then ISDN base and primary came along.

ISDN primary allows 30 channels x 64 kbts (in English 30 x calls or conversions at the same time)

ISDN base or ISND2 allows 2 x calls at the same time or 2 channels x 64 kbts.

ISDN is preferred over exchange lines because it allows:-

• Digital quality
• Offers call line id and a 10 number range for department calls.

So for instance if I had ISDN2's added to my business I could have a simply 2 x line / channel setup but with 10 numbers allocated to the service. This would allow DDi (direct dial in) to 10 x phones or 10 x departments (sales, accounts, etc).
If I wanted more channels / lines you tag together ISDN2's, so 3 x ISDN 2 would give you 6 x channels / 6 simultaneous calls in / out.

When you consider that some Teleco's will now provide ADSL service that has a minimum quality of service (ie better than ISDN2 bandwidth) the best route is ADSL with QoS.
Or if warranted MPLS (multi protocol line service)

The question is then what you want to do with both your voice and data.

On a small 3 retail site setup I'd imagine you would have 1 x main site / HQ and 2 x small node sites.

So you could have servers based at the HQ, primary VoIP at the main HQ and small node data and voice at the sub branches.

Get the Avaya IP Office SME sales bloke round, they sell a very handy little pile of boxes that will do all you want and need.

Small Business Phone System in UK - Avaya Â*-Â*IP OfficeÂ*-Â*Prod Overview


You could then have EPOS at all branches with stock update to a central server.
Virtually free phone calls between branches.
Centralise mail services.
Central management of PC's, broadband access, phones (and what they can do- dial out restrictions).
Access to stats regarding call volumes and costs.

Over the last few years many businesses with multiple sites have taken to such services. Take a BS branch system.

Once they had phones and phone lines, data links for PC's. Now they have 1 x data service via DSL or MPLS which does the lot.

You will here the words QoS (quality of service) which is always the main issue.

A voice call uses about 40 kbts to set up and about 20 kbts once connected. Voice is real time, and as such MUST connect or be lost. Where QoS Voice comes in is to analyse your requirements and make sure that at all times bandwidth is available to allow VoIP to function.

In the old days of low bandwidth broadband contention was the issue. So broadband at home during the day offered max and at night (with all the neighbours on) was squeezed to a point where the service was barely adequate.

It's still the same, but since the bandwidth have increased the contention has become less of an issue.

BT and a heap of Telco's all have business quality broadband that will allow VoIP to be end to end 24/7 without any risk of calls being lost due to lack of bandwidth.

You would require 3 x DSL connections- 1 x decent bandwidth at HQ and 2 x modest bandwidth at the branches.

The IP office kit at all locations and then some servers for the HQ.


I've not done Telecoms sh1te since I walked away 6 years ago. So although what I say is correct, service offerings and my knowledge base isn't up to the minute

[Mac]

A voice call uses about 40 kbts to set up and about 20 kbts once connected. Voice is real time, and as such MUST connect or be lost. Where QoS Voice comes in is to analyse your requirements and make sure that at all times bandwidth is available to allow VoIP to function.

Things have changed rapidly over the last couple of years Chris - as technology does. Since MS' introduced their adaptive codec other vendors are running to catch up. Cisco with their ILBC (Internet Low Bandwidth Codec) for example. QoS was always massively misunderstood anyway - there's no such thing as a free lunch after all. If your network regularly requires the QoS rules to kick in you have some worries after all.

The future is software in telephony The traditional IP-PBX vendors can't keep up with software based platform development. Things like Cisco CallManager, Mitel 3300s, Nortel (Ha!) are all dead in the water. Cisco have been sh*tting their pants the last two years because of the length of their development cycle - still, they seem to be getting back with the program.

[johnny11]

the other option they may offer you is a isdn 30 but you only have i.e 5 channels to begin with then if you want more its easy to add more, but you do have to have the phone system onsite which you buy and have a contract, and i know you can do a deal with a isdn 30 that incudes all calls, but this prob isn`t the cheapest option.

[Chri5]

ISDN prim starts at £3k for installation, even if you start with a low channel use.

I'd listen to Mac and await his suggestions for a model based on your requirements.

On that subject is it only voice or would you consider an intergrated data and voice service. Reason I ask is that my now limited knowledge still suggests that a bundled (voice and data) service is the way forward and the best ROI route.

VoIP tends to use SIP based phones, which are really just partners to existing PC desktops with IP addresses. The other alternative is a soft phone, which is a PC with software that allows the PC to be both a voice and desktop use item.

If all the tech stuff seems OTT do consider that the stats indicate that the old fashioned key system or PABX still accounts for 50% of sales in the sme arena. So old is still well sold, and new sells on the basis of economy when you bundle the 'whole' communications (voice, data, intergrated messaging and mail, voice mail etc) together.

ISDN is an old technology, and although it has been usurped by DSL and MPLS it still works, is well known, and has no support or engineering build issues.

Cisco were the main corp players in VoIP via CM products, but even they don't get it right. The Aus NSW police had 25,000 VoIP phones and removed them all within a year