3 September 2026LANTEK Computers
A PABX in a cupboard is one of those things a business stops seeing. It was installed by somebody who has since moved on, it has a maintenance line item nobody questions, and it works, mostly, until a handset dies and the replacement costs more than a laptop.
Moving that onto Teams Phone means your phone system stops being a box on a wall and becomes part of the same system your staff already sign in to. That is genuinely simpler. It is not, however, a like for like swap, and the places it differs are worth knowing before you commit.
What actually gets better
One identity instead of two. Today somebody has a computer login and, separately, an extension. With Teams Phone the extension belongs to the person, so their number follows them to a desk, a laptop or a mobile without call forwarding rules that somebody has to maintain.
Working from anywhere stops being a special arrangement. A staff member at home answers the company number from the same app they use for meetings. No diverts, no personal mobile given out to a client and never taken back.
Changes stop being a call-out. Adding a person, changing a name on the directory, moving somebody between departments: these become admin tasks rather than a visit from a technician who bills for the trip.
You stop maintaining hardware that only does one thing. No PABX to keep alive, no proprietary handsets to source, no maintenance contract on a box whose manufacturer may or may not still support it.
What you have to plan for, and what people underestimate
Porting your numbers is a process, not a setting
Your existing numbers can move. That is the normal outcome and it is what you should insist on, because a business changing its published number quietly loses every enquiry from every place that number is printed.
What matters is that porting involves your current provider, your new one, and paperwork that has to match your records exactly. Company name, registration number and the service address all have to agree with what the losing provider holds. This is the single most common cause of delay, and it is entirely avoidable: get the account details in front of you and confirm they are current before anybody submits anything.
Plan the port as its own step with its own date, and do not schedule anything else on top of it.
Reception is the real design work
Everybody focuses on handsets. The thing that takes actual thought is how an incoming call to the main number gets to a person.
On an old PABX that logic accumulated over years, and usually nobody has a written record of it. Before you move, write down what currently happens: who the main number rings, in what order, what happens if nobody answers, what happens after hours, what happens over the December shutdown, and who has the ability to change any of it. That document is the specification for the new system, and producing it almost always uncovers rules that no longer reflect how the business runs.
If you have somebody who answers the phone all day, involve them. They know things about your call flow that no diagram does.
The things plugged into the old system
This is where a move gets interrupted. A PABX usually has more attached to it than the handsets.
- The intercom at the gate
- The lift telephone, which may be a legal requirement to keep working
- An alarm panel that dials out over a phone line
- The card machine, if it is not on the network
- A fax number that one supplier or one regulator still uses
- The overhead paging system in a warehouse
- A door strike that a receptionist releases by pressing a key on a handset
None of these are unsolvable. All of them need finding before the old system is switched off rather than after. Walk the building and look for anything with a cable running to that cupboard.
What happens when the line drops
This is the honest objection, and it deserves a straight answer rather than reassurance. An internet based phone system depends on your internet. If the fibre is cut, or the power is off and nothing is holding the network up, the desk phones stop.
The mitigations are real, and they are what you should be asking a provider about:
Calls fail over to mobiles. Because the number belongs to the person rather than the desk, an unanswered call can route to a mobile automatically. Configured properly, an outage means staff answer on their phones rather than the business going silent.
A second internet path. A backup connection on a different medium is the thing that keeps everything else working during an outage too, not only the phones.
Something holding the network up. A router and switch on battery is a small cost and it is what determines whether an hour of load shedding takes the phones with it. This matters more here than most places, and it is worth reading alongside what load shedding does to your data.
Worth saying plainly: an old PABX had the same dependency on power, and usually less protection. The difference is that the failure is more visible now, so it gets planned for.
Audio quality is a network question
If calls sound poor, it is almost never the phone system. It is the network underneath it, and specifically whether voice traffic is prioritised over everything else competing for the same connection.
On a network that was never designed for voice, somebody uploading a large file can make a call unusable. This is fixable and it is ordinary work, but it is work, and a provider who tells you nothing needs to change on the network has not looked.
Do you still need desk phones
Often fewer than you think. A person at a computer all day is generally better served by a good headset than a handset, and the handset budget is better spent on the headsets.
Where a physical phone still earns its place: reception, a shared area where anybody might need to make a call, a warehouse or workshop where nobody has a computer, and the boardroom. Buy for those and skip the rest.
A sensible order to do it in
One, document the current call flow and find everything attached to the old system. Two, check the network can carry voice and fix it if it cannot. Three, get the account details for porting confirmed and correct. Four, build the new call flow and test it on internal calls before any number moves. Five, port the numbers, with the old system still available. Six, run both briefly, then decommission.
The overlap in step five is the same principle as any other migration: nothing user facing moves until it has been rehearsed, and there is always a way back.
Where to start
If you are weighing this up, the useful first step is not a quotation. It is the call flow document, because it tells you how complicated your situation actually is, and you can produce it yourself in an hour.
What we cover is set out on Teams Phone, and the network side sits with IT Infrastructure. If you would rather talk it through, telephone us, which feels like the right way to start this particular conversation.