12 Mobility Billing Errors That Go Unnoticed (and Cost Enterprises Thousands)

Most enterprise mobility bills contain hidden errors and not just small ones. In our audits, it's common to uncover 5-15% in overcharges that have gone undetected for months or even years.

The reason? Many billing mistakes are buried deep within carrier invoices, hidden behind line items and codes that most finance or IT team don't have the time or resources to analyze. Unless you know where to look, these errors can quietly drain budgets.

Here are 12 common billing errors we regularly find during mobility audits, why they happen, and how they impact your bottom line.

Legacy Plan Retention Charges

Lines remain on outdated, higher-cost plans even though cheaper, equivalent plans are available. This often happens during bulk migrations where certain lines are missed.

Example: One client had negotiated new IoT pricing, yet some lines were still billed at legacy rates. We quickly identified these lines and updated the plans in the carrier portal to avoid further overcharges.

Incorrect Feature Billing

Paid add-ons are billed even when unused or when a comparable free feature is available. This typically occurs when features are removed but not properly updated in the carrier's billing system.

Double Billing for the Same Line

The same line appears under multiple account numbers. This is common during migrations from one carrier to another, when the original line is never full disconnected.

Roaming Overcharges Despite a Roaming Packages

Lines have active roaming plans but are still billed at pay-per-use rates.

Example: Some vendors ensure all lines have an international roaming feature such as Travel Pass or Day Pass, but if a feature is dropped during a plan change, the client can incur significant roaming charges.

Misapplied Contract Rates

Contract discounts are not applied consistently, often overlooked when new lines are added and not coded with the correct discount structure.

Billing for Disconnected Lines

Lines continue billing after cancellation requests because orders aren't fully processed by the carrier.

Usage Rating Errors

Calls or data usage are incorrectly rated due to zone misclassification.

Example: Calls from the U.S. to Canada billed at a higher pricing tier instead of the lower, correct rate.

Device Installment or Lease Overcharges

Device lease charges continue after a buyout or return. This often happens when devices are swapped mid-term but the old lease billing isn't stopped.

Taxes and Surcharges Miscalculated

We see cases where certain surcharges, such as regulatory or administrative fees, are applied more than once across multiple accounts or billing levels. Over time, these small overcharges can quietly add up to thousands of dollars in unnecessary costs.

Data Overage Charges Despite Pooled Plans

Miscalculations in pooled data data plans cause overage charges even when total usage is well below the pool limit.

Example: We've seen AT&T accounts incur usage charges despite pooled utilization being well under 100%

Billing for Unused/Inactive SIMs

Monthly access charges continue for SIMs cards sitting in storage, especially common in IoT and M2M deployment.

Promotional Credits Not Applied

Promised credits from renewals or promotions never appear on the bill, often due to internal carrier processing errors.

Final Thoughts

Mobility billing errors aren't just inconvenient, they can quietly drain tens of thousands of dollars from annual budgets. Identifying these issues requires a detailed, line-by-line review of invoices, contracts, and carrier systems, along with the expertise to spot patterns that carriers' systems often overlook.

If you suspect your mobility bill contain hidden overcharges, let's connect to see if a review could uncover meaningful savings.