Every IT decision maker has heard the pitch: ditch your PBX, go VoIP, save money. But the real story is more nuanced. VoIP is the right call for most organizations — but understanding exactly why helps you build the business case and avoid the pitfalls that sink poorly-planned migrations.
The Core Difference
Traditional PBX routes calls through the PSTN using dedicated physical lines. VoIP converts voice into data packets and routes them over your existing IP network. This single architectural difference has cascading implications for cost, scalability, feature availability and maintenance overhead.
Where Traditional PBX Still Has Ground
Reliability in low-bandwidth environments is the honest answer. If your office has inconsistent internet connectivity, a PBX with PSTN fallback offers more predictable call quality. PBX also has a longer hardware lifespan. If your call volume is low and your needs are static, the capital already deployed isn't wasted.
Where VoIP Wins Decisively
Scale, features and cost. Adding a new line on a PBX means buying hardware. On VoIP, it's a configuration change. Features that cost thousands to license on PBX — call recording, IVR, auto-attendant, analytics — come standard on a platform like Express IVR. International calling costs drop dramatically.
The Migration Risk Most Companies Don't Plan For
Number porting. Moving your existing phone numbers from PSTN to VoIP requires coordination with your current carrier and your new provider. If not managed carefully, you can lose calls during the transition window. Always insist on a parallel-run period.
Bandwidth planning is where most VoIP migrations encounter their first obstacle. A standard VoIP call requires roughly 80–100 kbps of bandwidth per concurrent call, including overhead. For an office of 50 people with 20 concurrent calls at peak, you need at least 2 Mbps dedicated to voice — separate from general internet traffic. QoS (Quality of Service) configuration on your router ensures voice packets are prioritized over bulk data transfers.
The softphone question comes up in every VoIP evaluation. Most platforms offer both desk phone compatibility (via SIP) and software clients for laptops and mobile devices. The right choice depends on your team's workflow: desk-bound roles often prefer the tactile feedback of a physical handset; mobile or hybrid workers typically prefer the flexibility of a softphone. Many deployments run both, with users switching between them transparently.
Vendor lock-in is a legitimate concern. Some VoIP platforms use proprietary signaling protocols that make migration to another provider expensive. SIP-based systems — the open standard — give you portability: your numbers, your call flows and your configuration can move with you if you change providers. Always ask about SIP compliance and number portability before signing a contract.
Ready to modernise your voice infrastructure?
If you're comparing VoIP options or planning a migration, Express IVR can assess your current infrastructure and recommend a path that minimizes disruption. Most of our migrations complete with zero downtime.
