The Network Readiness Check to Run Before You Move to VoIP

When calls break up after a move to VoIP, the phone system gets blamed. It is almost never the cause. The cause is usually a network condition that existed beforehand and had nothing to test it — browsing and email tolerate the kind of jitter that makes a voice call unusable.

Half a day of checking in advance is the cheapest insurance available on a phone migration.

Measure the right things

Speed tests are close to useless here. Voice needs about 100 kbps per call in each direction, which any business connection has. The three numbers that matter are different:

• Jitter — variation in packet arrival. Under 30 ms is comfortable. This is the usual culprit.
• Packet loss — anything sustained above 1% is audible as clipped words.
• Latency — under 150 ms one way keeps conversation natural.

Measure them at your busiest hour, not at eight in the morning. A connection that is clean when the office is empty tells you nothing. The bandwidth guide covers what to expect.

Count your simultaneous calls, not your staff

Capacity is sized on concurrent calls, and the number is almost always lower than people assume — a twenty-person office rarely exceeds six at once. Pull a month of call records and look at the peak. It decides how many channels you need and it is the difference between paying for capacity you use and capacity somebody guessed at.

Look at the equipment in the path

Three things cause most trouble:

A router doing SIP ALG. A feature intended to help VoIP that frequently breaks it. It is on by default on a lot of consumer-grade equipment and should be turned off.

No quality-of-service configuration. Without QoS, a large upload competes with your voice traffic and wins. The QoS guide has working configurations for common routers.

Unmanaged switches and old cabling. Worth checking where the building has never been rewired — and worth confirming there are data points where the phones will actually sit.

Power over Ethernet, and what happens without power

Desk phones are usually powered over the network cable, which needs a switch that supplies it or an injector per phone. Check this before the handsets arrive; it is the most common day-one surprise.

Then ask the awkward question: what happens in a power cut? Phones powered by the network go down with the switch. A small UPS on the router and switch keeps the phones alive through short outages, which in Jamaica is worth planning for rather than discovering.

The one test that predicts everything

Before committing, run real calls over the actual connection at the actual busy hour for a week. Not a simulation — a handful of staff using it for real work. Everything above is diagnostic; this is the test that tells you whether it will be fine.

Frequently Asked Questions

How much bandwidth does a business really need for VoIP?

About 100 kbps per simultaneous call in each direction. Stability matters far more than headline speed.

What is SIP ALG and why turn it off?

A router feature meant to assist SIP traffic that in practice rewrites it incorrectly. Disabling it resolves a large share of one-way-audio and registration problems.

Do I need a dedicated connection for voice?

Not usually. Correctly configured QoS on a shared connection is enough for most offices; dedicated access is worth it where call volume is high or the connection is contended.

What if the readiness check fails?

Most findings are fixable in a day — a router setting, a QoS rule, a switch. The ones that are not are worth knowing about before you move rather than after.

Getting started

Run the checks a fortnight before the planned switch so there is time to fix what turns up. The 30-day migration checklist puts this in sequence with everything else, and the WOCOM team can run the assessment with you.