As the unbelievably reliable and rugged Nortel systems out there get up in age, owners of these systems begin thinking "what is the migration path for my phone system?"
In case you didn't know, Nortel was dissolved in 2009 and sold off in three parts at auction. The part of the company that deals with business phone systems was acquired by AVAYA.
Avaya wasted no time in informing all the Nortel Norstar owners that their systems would be "out of support" in short order. Avaya's solution was that you upgrade to an "Avaya IP Office". Unfortunately, many did. From my experience in the field many of those who upgraded were not as happy with the new Avaya IP Office as they had been with their previous Nortel Norstar systems.
As far as upgrading is concerned, I will propose three possible paths (although there are more, to be sure).
1. Upgrade to an Avaya IP Office (and go through the learning-curve)
2. Upgrade to an entirely different provider such as Cisco, Samsung, or other. (learning-curve)
3. Upgrade to a E-Metrotel UCx (and keep the good old Nortel experience you're used to).
First the IP Office:
If you get warm fuzzies from sticking with brand loyalty that has treated you well in the past, then Avaya is your solution. Nortel no longer exists, but Avaya is the company that bought their phone system business. But, to be clear, the Avaya culture is NOT the same as the Nortel culture.
While the Avaya product does not resemble the Nortel product, it is possible to leverage existing Norstar telephone sets with and Avaya backend phone system. From what I have heard in the field, it's been a luke-warm reception. The Norstar phones do work as they did before, for the most part, but technicians have told me it's pain to work with.
The other Avaya option is to go 100% fork-lift upgrade (meaning throw out everything and get all new). This puts an Avaya IP Office handset on every user's desk. There will be a learning curve. And, there is the potential to get all kinds of new, killer applications for Unified Communication.
Personally, I do think the Avaya IP Office is a very cool looking system. The aesthetics of the upper-end phones (96XX series) are very inviting. And, the Unified Communication tool will blow your mind (tablet integration, video).
I have two major complaints with Avaya IP Office systems:
1. Every time you turn around, there's a fee for licensing, maintenance, or upgrades. Avaya insist that if you want to maintain support from them, the system must stay upgraded within at least 2 major releases. For example if you're on version 7.1 and the current version is 9.1. You'll need to upgrade to at least 8.0 in order to receive support.
2. Flakey behavior. I've been working on these systems a few times a month. There are some behaviors that I find confidence-shaking. For example. Sometimes the system will develop behavior quirks that are only remedies by rebooting. No cause was found - just reboot and the problem goes away.
Another is that the database (the place where program settings are stored) can become corrupted. Some of this may be due to the fact that information is stored on a little SD card in the unit. SD memory is not perfect.
On balance, you won't go wrong if you upgrade to Avaya's option. But, there may still be better choices for you.
Upgrading to something entirely different:
If you're thinking of upgrading the Nortel system, now would be the time to consider something entirely different. I know, we love the Nortel and we hate to see it go. But, that era is over now (well, except for the UCx which I'll talk about next).
One system that I see a everywhere these days is the Cisco phones. One of the things that is very attractive about Cisco phones is they integrate well if you already have a Cisco network infrastructure. Cisco phone are 100% Voice-over-IP (aka: "VoIP"). That means, they run just like network devices. They do not require a separate phone wire infrastructure. (in fairness Avaya IP Office make both VoIP and non-VoIP phones).
I find the network administrators, especially those who are well verse in Cisco technology, love the Cisco phones because they are managed very much like the rest of the Cisco network infrastructure.
Polycom is another good choice. Polycom is also 100% VoIP solution. And, it is an especially good choice if you are thinking of going with a non-local, cloud-based phone system. This means that instead of having the phone system server (pbx or key system) locally on your premises, the phone system is something that lives in the cloud. Usually, there is a monthly service fee you pay for this. However, there can be some really cool advantage to having a cloud-base phone system. Portability and disaster resilience are two of the big ones!
Poycom makes a good choice for small and mid-sized office environments that don't require sophisticated call handling. Thee telephone sets are very affordable. Also, I mentioned portability. For instance, taking your office phone home with you and plugging it in a home is something the Polycoms can facilitate pretty easily (Cisco and Avaya can too, it' just not as easy to setup).
One complaint I have had with Polycom is that many people are used to "line appearances". That refers to a "line 1, line 2, line 3, etc." universal appearance on every phone. The reason we, as users, like this is it gives us a simple method for transfering calls. We put the call on hold and then just inform the desired party to retrieve the all from the appropriate line.
In the Polycom world (and with many other VoIP phones) the line appearance concept goes away and is replaced by "call appearances". Call appearances are a little less linear in that they do not universally appear the same on every phone. It can take a while to get used to.
There a whole myriad of other brand choices. I can't speak to them as well, because I don't encounter them much in my work travels. Right now (2015), what I see the most of out there is Avaya, Cisco, Polycom and the old Nortels.
E-metrotel's UCx platform
If you currently have a large installation of Nortel phones. Upgrading to something completely new can be very expensive. Mainly, because the cost of the desk telephone are what drives a large portion the total solution. Here's some quick math to give an example:
Avaya PBX (small) is about $2500
each Avaya desk phone (basic) is about $200
replacing a small office of 8 phones is about $5000 (including the install/training costs).
But, a larger installation where there are 100 desk phones looks like this:
Avaya PBX (medium) $8000
each Avaya desk phone @ $200 = $20,000
So, roughly $30,000 for that scenario.
Now, imagine if you could replace only the PBX (the phone system brain). That same installation would be about $10,000 (including install costs).
That's where E-metrotel's UCx comes in. They make a system that seamlessly replaces the Nortel back-end PBX. You literally could upgrade the system on a Friday night and your phone users would even know the difference on Monday morning.
Why? because the phones are the same and they work the same way they used to.
But the real kicker is that you get all these new, cool Unified Communications tools that you would expect from a modern system.
And, you're not locked in to only using Nortel phones. As your phones wear out you can choose to replace them with the abundance of surplus that is out there. Or, you can elect to go with another brand of phone such as a Polycom.
Wrapping it up
There is no BEST OPTION here. The solution that is best for you depends on your situation and you're tolerance for change. I have a personal bias because I am such a fan of the Nortel system that of course I would be gunning for the UCx solution. However, if I were making a recommendation for you as one of my clients, I would weigh all the different factor in your environment.