If you are a wireless customer with AT&T, chances are your monthly bill just increased by $1.23.

As first noticed by BTIG Research analyst Walter Piecyk and reported by The Verge, AT&T decided to quietly increase the administration fee on every standard, monthly wireless customer's bill. The fee used to be $0.76, but now it's more than double that at $1.99 every month.

Unless you keep close track of your bills, you'd be forgiven for not spotting that extra $1.23 every month, but for AT&T it's huge. The fee hike applies to 64.5 million customers, meaning an extra $800 million in revenue each year. That will come in very handy when trying to recoup the $85 billion the company just paid for Time Warner.

As to why the fee increased, an AT&T spokesperson told The Verge that, "This is a standard administrative fee across the wireless industry, which helps cover costs we incur for items like cell site maintenance and interconnection between carriers."

Did cell sites and interconnections suddenly get $800 million more expensive to maintain every year? That seems very unlikely. If you're a customer who will have to pay this increased fee, start asking questions. The more that do, the more pressure AT&T will face to give a better explanation or maybe even rethink the size of the increase.