When we run a voice audit, we don’t start with the phone bill. We ask for every cost related to telephony, wherever it lives in the accounts: the maintenance contract, the IT hours logged against handset problems, the capital spent on the PBX, the emergency technician callout from the day the phones died before a board meeting.

The pattern is remarkably consistent. The real monthly cost of business telephony comes out at 2.5 to 3 times the carrier invoice. A business paying $800 a month for its phones is usually carrying a telephony burden of over $2,000, and most of it never appears on anything labelled “phone bill”.

The maintenance contract that outlived its value

Somewhere in your accounts is a PBX maintenance contract, probably $300 to $800 a month depending on system size. It promises four-hour response and replacement parts. What it delivers, on the day you need it, is often a two-day wait for a technician who then discovers the part is obsolete and has to be sourced from overseas, while your receptionist forwards calls to her mobile.

These contracts auto-renew unless cancelled well in advance, often 90 days. Businesses keep paying them for years, partly through forgetting and partly through fear of being uncovered. Paying premium rates for insurance on hardware that’s becoming uninsurable is one of the purest forms of telco waste we see.

Line rentals from another era

Legacy voice lines still command premium rates because carriers know exactly how locked in their remaining customers feel. Businesses running banks of old-style line rentals for their call capacity are routinely paying $1,300 to $1,600 a month for what SIP trunking delivers for $400 to $600. The carriers are in no hurry to point this out.

The same era gave us the call rates. Contracts negotiated years ago still bill local calls by the minute and carry inbound charges nobody remembers agreeing to, while the current market standard is unlimited national calling included. If your voice contract hasn’t been to market in five years, your call rates are almost certainly above it.

Hardware depreciating in a cupboard

Then there’s the PBX itself. A $15,000 system bought to support 100 users, now serving 40, half of whom work from home and use it barely at all. The capacity was paid for up front and depreciates in the server room regardless of use. Cloud voice platforms invert this: you pay per active user, per month, and the number flexes with your headcount. For a shrinking or hybrid workforce, the difference compounds every year.

Adding it up honestly

Take the carrier bill, add the maintenance contract, the depreciation, the support hours and the occasional emergency, and the true number emerges. That’s the figure worth comparing against a modern alternative, and the comparison is rarely close. When we rebuild a voice environment (SIP capacity, calling inside Teams, no maintenance contract, no hardware), the ongoing cost typically lands well under the old carrier bill alone, before counting everything else that stops being necessary.

A Telco Health Check includes exactly this exercise: your full telephony cost assembled honestly, compared against what the same capability costs today. If your phone system is more than five years old, the number will be worth seeing.