An inmate uses a phone at the Cook County Jail in Chicago in 2014. (Charles Rex Arbogast/AP)

SOME PRISON inmates rely on letters or visits from family and friends to keep in touch with the outside world. But for countless others, the only viable way to communicate with loved ones is through phone calls. These calls are often timed, recorded and prohibitively expensive. It can cost up to 21 cents per minute to make phone calls between states — and for calls within states, rates can go over $1 per minute. As a result, phone bills may run up to hundreds of dollars a month — a financial burden that many inmates and families can ill afford.

Because prisons receive commissions from their contracts with phone companies, they tend to choose the service providers that offer them the best kickbacks, not the ones that offer the best and most affordable services to inmates. The providers, meanwhile, try to make up the cost of these kickbacks by charging higher fees. The result is a system that profits from the vulnerability of those behind bars.

Noting that phone rates should be “just, reasonable and fair for all Americans,” the Federal Communications Commission has capped rates on prison phone calls between states. But after a federal appeals court ruled that the FCC did not have the authority to regulate intrastate calls, calls within states have become even more costly — and the situation could soon get worse.

In May, Securus Technologies, one of the two largest prison phone companies, announced that it would be acquiring Inmate Calling Solutions, one of its last remaining competitors. If the deal is approved by the FCC, two firms — Securus and Global Tel Link — would control as much as 90 percent of the market. Through partnerships with other companies, they already have stakes in most of the remaining market share, so the acquisition would essentially create a duopoly in an industry that already suffers from lack of competition. This would give the companies even more power to enter into exploitative contracts with prisons.

Beyond the antitrust concerns related to the merger, civil society groups have argued that Securus does not meet the “character qualifications” required to hold an FCC license. The FCC previously found that Securus had provided false and misleading information to the commission in an attempt to expedite a review. The company has also come under criticism for creating a website that allowed law agencies to track non-inmates without permission, potentially in violation of privacy protections.

The FCC is currently reviewing the deal to assess its implications for market competition and the “public interest.” Given the behavior of prison phone companies and Securus’s own track record, it should thoroughly investigate these questions and delay a decision on the merger until they are answered. Blocking the acquisition would not solve the underlying issue of exorbitant prison phone rates; that is a problem for Congress and states to tackle. It would, however, deliver a deserved rebuke to profit-hungry prison phone companies and the correctional facilities that have enabled them.