For years, Ben Black’s cellphone irritated his household. It was the one Android gadget in a household message group with eight iPhones. Due to him, movies and photographs would arrive in low decision and there can be inexperienced bubbles of textual content amid bubbles of blue.

However a brand new app referred to as Beeper Mini gave him the power to alter that.

Mr. Black, 25, used the app to create an account for Apple’s messaging service, iMessage, together with his Google Pixel cellphone quantity. For the primary time, each message the household exchanged had a blue bubble and members had been in a position to make use of perks like emojis and animations.

Because it was launched on Dec. 5, Beeper Mini has shortly change into a headache and potential antitrust downside for Apple. It has poked a gap in Apple’s messaging system, whereas critics say it has demonstrated how Apple bullies potential opponents.

Apple was caught abruptly when Beeper Mini gave Android gadgets entry to its fashionable, iPhone-only service. Lower than per week after Beeper Mini’s launch, Apple blocked the app by altering its iMessage system. It mentioned the app created a safety and privateness threat.

Apple’s response set off a recreation of Whac-a-Mole, with Beeper Mini discovering alternative routes to function and Apple discovering new methods to dam the app in response.

The duel has raised questions in Washington about whether or not Apple has used its market dominance over iMessage to dam competitors and power customers to spend extra on iPhones than lower-priced options.

The Justice Division has taken curiosity within the case. Beeper Mini met with the division’s antitrust legal professionals on Dec. 12, two individuals acquainted with the assembly mentioned. Eric Migicovsky, a co-founder of the app’s mother or father firm, Beeper, declined to touch upon the assembly, however the division is in the course of a four-year-old investigation into Apple’s anticompetitive habits.

The Federal Commerce Fee mentioned in a weblog submit on Thursday that it might scrutinize “dominant” gamers that “use privateness and safety as a justification to disallow interoperability” between providers. The submit didn’t title any firms.

The battle additionally caught the eye of the Senate Judiciary subcommittee on antitrust. The committee’s management — Senators Amy Klobuchar, Democrat of Minnesota, and Mike Lee, Republican of Utah — wrote a letter to the Justice Division expressing concern that Apple was snuffing out competitors.

Apple declined to touch upon the letter.

The questions coming from Washington minimize to the guts of immediately’s smartphone competitors. Rival smartphone makers credit score iMessage with serving to Apple develop its smartphone market share in the USA to greater than 50 % of smartphones offered, up from 41 % in 2018, in keeping with Counterpoint Analysis, a expertise agency.

Messaging has been a key a part of Apple’s technique to promote extra iPhones. For years, it has made exchanges between iPhones and Android gadgets as primary because the texts between decades-old flip telephones. Texts between iPhone customers seem in blue and will be tapped to offer a thumbs up, however texts with Android customers seem in inexperienced and haven’t any easy perks.

Android firms have tried to battle again. An Android smartphone maker, Nothing, has collaborated with an app referred to as Sunbird to supply iMessage. Google, which has developed the Android working system, has pressured Apple to undertake a expertise referred to as wealthy communication providers, which might make it potential to ship high-resolution video and pictures between competing smartphones.

However their efforts haven’t made a lot of a dent. Final month, Apple mentioned it might undertake the expertise within the coming yr. The transfer means Android customers will get pleasure from advantages like sharing higher-resolution movies however be caught with the inexperienced bubbles for textual content messages, which have change into stigmatized and related to much less wealth.

“Everyone seems to be watching to see what sort of response Apple goes to must Beeper Mini,” mentioned Cory Doctorow, a particular adviser to the digital rights advocacy group Digital Frontier Basis who has written a guide about interoperability throughout completely different applied sciences. “We are able to’t inform how anxious they’re internally, however their response may have a huge effect on how messaging works.”

Defending iMessage is a decade-old technique at Apple. In 2013, Craig Federighi, Apple’s head of software program, opposed making iMessage workable on opponents’ gadgets as a result of it might “take away an impediment to iPhone households giving their children Android telephones,” in keeping with emails launched throughout the firm’s courtroom battle with Epic Video games, the maker of Fortnite.

Tim Prepare dinner, Apple’s chief govt, has resisted calls to alter that place. He informed an iPhone proprietor at a convention final yr that the answer to inexperienced textual content messages was to purchase iPhones for family and friends members.

Beeper introduced a unique method to messaging. Mr. Migicovsky created the corporate in 2020 to construct a single messaging app that would ship texts throughout a number of providers, together with WhatsApp and Sign.

Mr. Migicovsky managed to combine most messaging providers, besides iMessage. In contrast to its friends, Apple didn’t supply an internet app, making it troublesome to attach with its service. The one approach Beeper may combine iMessage was to route messages by way of Mac computer systems after which to an iPhone. The method delayed messages and made them much less safe.

As Beeper struggled with iMessage, a young person in Bethlehem, Pa., discovered an alternate answer. James Gill, a 16-year-old laptop hobbyist, made it his private aim to determine how iMessage labored. He used software program to decrypt his iMessages and decided that Apple used its push notification system — the identical one which delivers information alerts — to ferry messages between gadgets.

“It wasn’t genius perception,” mentioned Mr. Gill, a junior at Saucon Valley Excessive Faculty. “I used to be simply poking at it for a very long time.”

In June, Mr. Gill printed his findings on GitHub, a software program platform the place programmers share code. When Mr. Migicovsky noticed the submit, he thought it may assist Beeper clear up its iMessage downside. He provided Mr. Gill a job making $100 an hour, a serious enhance from the $11 an hour the excessive schooler was making as a cashier at McDonald’s.

The job has been extra concerned than Mr. Migicovsky or Mr. Gill anticipated. Since Beeper Mini’s launch this month, Apple has modified iMessage about thrice, Mr. Migicovsky mentioned.

Every change by Apple required an adjustment by Beeper. Its newest answer includes routing registration data to Beeper Mini customers by way of their private Mac computer systems.

“To dam it fully, they’ll must provide you with a approach to require an iPhone serial quantity,” Mr. Gill mentioned. “Beeper will nonetheless provide you with a workaround.”

An Apple spokeswoman mentioned it might proceed to replace iMessage as a result of it couldn’t confirm that Beeper stored its messages encrypted. “These strategies posed important dangers to consumer safety and privateness, together with the potential for metadata publicity and enabling undesirable messages, spam, and phishing assaults,” she mentioned in a press release.

Mr. Migicovsky disagrees. As a substitute of permitting Android prospects to ship encrypted messages to iPhone prospects, he mentioned, Apple is making an attempt to power them to alternate unencrypted textual content messages. He has posted Beeper’s software program code on the net and inspired Apple and cybersecurity consultants to evaluate it.

Matthew Inexperienced, an affiliate professor of laptop science at Johns Hopkins College, mentioned Apple had some official safety issues and warned that an prolonged battle between the 2 firms may doubtlessly introduce vulnerabilities that criminals may exploit.

“A world the place Apple works with third-party shoppers in a supported approach is an effective one,” Mr. Inexperienced mentioned. “A world the place Beeper and Apple attempt to battle one another in a tit-for-tat arms race is a nasty one.”

In an try to finish the standoff, Mr. Migicovsky mentioned, he emailed Mr. Prepare dinner, however Apple’s chief has not responded.

“This wasn’t our intention,” Mr. Migicovsky mentioned. “We’re making an attempt to make it work, inside our management, for the great of the chat world.”