Your office phone bill is one of the last places where many Singapore SMEs still pay 2010 prices for 2010 technology. This guide walks through the voip vs traditional phone trade-offs honestly – cost, reliability, what breaks in a power cut – with Singapore numbers, so you can decide whether it is finally time to switch.
The real difference: a dedicated line vs your internet
A traditional phone line is a dedicated circuit from your office to the telephone exchange – you rent the line itself, per line, whether anyone calls or not. VoIP (Voice over IP) sends calls over the internet connection you already pay for, as data. That one change drives everything else: pricing moves from per-line rental to per-user subscription, adding a line becomes a software change instead of a site visit, and your “phone system” becomes an app that lives wherever your team does – desk phone, laptop or mobile.
VoIP Singapore: what actually changes here
The VoIP Singapore picture is unusually favourable, for three local reasons:
- The whole island is fibre. Singtel switched off its copper ADSL network back in 2018, and office broadband here is overwhelmingly high-speed fibre – the unreliable-internet argument against VoIP mostly does not apply in Singapore.
- It is properly regulated. VoIP providers operate under IMDA licensing, and IMDA allocates dedicated 8-digit numbers starting with “3” for IP telephony services – a VoIP number here is a real, regulated Singapore number, not a workaround.
- You can keep your number. Singapore supports fixed-line number portability, so the 6-prefix number on your signboard and name cards can move to a VoIP provider in most cases. IMDA’s Fixed Number Portability Guidelines set out how operators port level-6 fixed lines.
Providers range from the big telcos to local specialists – entry systems are advertised from around S$49 per month – and desk handsets are commodity hardware now: entry IP phones like the Yealink T31 series sell in Singapore for roughly S$78-S$169, with mid-range models around S$200.
Cost: line rental vs per-seat
| Cost item | Traditional lines | VoIP |
|---|---|---|
| Monthly cost | ~S$20-S$40 rental per line | ~S$5-S$15 per user |
| Hardware | PBX box + analogue sets | IP phone ~S$78-S$200, or none (softphone app) |
| Adding a line | New physical line, site visit | Software change, minutes |
| Overseas calls | IDD rates | Internet rates, often a fraction of IDD |
| Moving office | Relocate lines, re-cable | Plug phones into any internet connection |
| Features (IVR, recording, ring groups) | Extra hardware or unavailable | Included in most plans |
For a 10-person office running four traditional lines, the rental alone often exceeds what ten full VoIP seats cost – and the VoIP seats each carry voicemail-to-email, call routing and a mobile app. The savings compound if your team calls overseas.
Reliability: the honest trade-offs
Traditional analogue lines have one genuine advantage: the line itself carries power, so a basic corded phone keeps working in a blackout. VoIP depends on your power and internet. The mitigations are standard and cheap – a small UPS on the router and PoE switch, and automatic failover to the provider’s mobile app, which keeps calls flowing on 4G/5G even if the office loses power entirely. On capacity: a VoIP call needs only about 100 kbps each way, so even a modest 500 Mbps office fibre line can carry hundreds of simultaneous calls – quality problems in practice come from misconfigured networks, not thin pipes, which is why we set up QoS (voice-traffic priority) on the office network as part of any rollout. The IETF’s DiffServ guidelines for telephony traffic set out which class voice packets belong in. Good network cabling and setup matters more to VoIP quality than the internet plan does.
When a traditional line still makes sense
- Lift emergency phones and fire-alarm auto-diallers – these are life-safety systems; many are certified against dedicated lines and should stay on them.
- Legacy fax and some payment or alarm terminals – test before migrating; some old devices misbehave over VoIP adapters.
- A deliberate blackout fallback – some offices keep one analogue line as insurance, though a mobile-app failover usually covers the same risk for free.
Notice what is not on this list: everyday staff calls. There is no longer a quality or regulatory reason to keep humans on analogue lines in Singapore.
How to decide
- Count your lines and their rental – the number on the bill, not the plan brochure.
- Price the same headcount as VoIP seats – include the one-time handsets if you want desk phones.
- List the exceptions – lift line, alarm, fax – and plan to leave them where they are.
- Check your network first – PoE for desk phones, QoS on the switch, UPS on the comms rack. This is where quality is won.
- Port your number – keep the number your customers know; it moves with you.
If the answer is switch, the next question is which system and which handsets – our VoIP phone system buying guide for Singapore SMEs covers exactly that, including what a voip phone singapore purchase actually costs by brand.
Frequently asked questions
Is VoIP cheaper than a traditional phone line?
Almost always, for offices. Traditional lines cost roughly S$20-S$40 per line per month in rental before a single call; VoIP seats run about S$5-S$15 per user per month with features included, and overseas calls route at internet rates instead of IDD. The main costs VoIP adds are one-time – desk phones at S$78-S$200 each if you want them – and a properly set up network.
What is the disadvantage of using VoIP?
VoIP depends on your power and internet – in a blackout, an unprotected VoIP setup goes down while an analogue line keeps working. The standard fixes are a UPS on the router and switch plus automatic failover to a mobile app. VoIP calls also cross the public internet, so quality depends on a well-configured network with voice prioritisation (QoS), which is a one-time setup task.
Can I keep my office phone number if I switch to VoIP?
In most cases, yes. Singapore supports fixed-line number portability, so your existing 6-prefix office number can usually be ported to a VoIP provider. New VoIP services are also issued regulated 8-digit Singapore numbers starting with “3”. Check porting support with the provider before signing – it should be a standard, documented process.
Can I use a VoIP phone as a regular phone?
Day to day, yes – a desk IP phone looks and behaves like the phone your team already knows: pick up, dial, transfer. The difference is behind the wall socket: it plugs into the network instead of a phone line, usually powered by the same cable (PoE). Your team needs almost no retraining, which is why hardware handsets remain popular even though a laptop or mobile app can do the same job.
Does VoIP work during a power cut?
Not by itself – no power means no router, switch or phones. Offices handle this two ways: a small UPS keeping the comms rack alive for the duration of a typical outage, and provider-side failover that automatically forwards calls to mobile apps or numbers over 4G/5G. With both in place, a power cut costs you desk phones for an hour, not your phone number.
Do I still need a phone line for the lift or fire alarm?
Treat lift emergency phones and fire-alarm auto-diallers separately from office telephony. These are life-safety systems, often certified against a dedicated line, and they should not be casually migrated to the office VoIP system. The standard pattern is: humans move to VoIP, life-safety devices keep their dedicated lines.
About the author
Written by the Rezolva IT team – we handle the network side of VoIP for Singapore SMEs: PoE cabling, QoS, UPS protection, porting coordination and the analogue exceptions that should stay analogue. The costs above are Singapore market rates as of August 2026.