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

However a brand new app known as Beeper Mini gave him the flexibility to vary 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 develop 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 without warning when Beeper Mini gave Android units 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 stated the app created a safety and privateness threat.

Apple’s response set off a sport of Whac-a-Mole, with Beeper Mini discovering other ways 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 drive shoppers to spend extra on iPhones than lower-priced alternate 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 accustomed to the assembly stated. Eric Migicovsky, a co-founder of the app’s guardian firm, Beeper, declined to touch upon the assembly, however the division is in the midst of a four-year-old investigation into Apple’s anticompetitive conduct.

The Federal Commerce Fee stated in a blog post on Thursday that it might scrutinize “dominant” gamers that “use privateness and safety as a justification to disallow interoperability” between providers. The publish 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 lower to the center of in the present day’s smartphone competitors. Rival smartphone makers credit score iMessage with serving to Apple broaden its smartphone market share in the US to greater than 50 p.c of smartphones bought, up from 41 p.c in 2018, according to Counterpoint Research, a know-how 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 units as fundamental 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 struggle again. An Android smartphone maker, Nothing, has collaborated with an app called Sunbird to supply iMessage. Google, which has developed the Android working system, has pressured Apple to adopt a know-how known as wealthy communication providers, which might make it attainable to ship high-resolution video and pictures between competing smartphones.

However their efforts haven’t made a lot of a dent. Final month, Apple stated it might undertake the know-how within the coming 12 months. 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 develop into stigmatized and related to much less wealth.

“Everyone seems to be watching to see what sort of response Apple goes to should Beeper Mini,” stated Cory Doctorow, a particular adviser to the digital rights advocacy group Digital Frontier Basis who has written a book about interoperability throughout totally different applied sciences. “We are able to’t inform how nervous they’re internally, however their response might 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’ units as a result of it might “take away an impediment to iPhone households giving their children Android telephones,” based on emails released throughout the firm’s courtroom struggle with Epic Video games, the maker of Fortnite.

Tim Prepare dinner, Apple’s chief government, has resisted calls to vary that place. He told an iPhone owner at a conference last year that the answer to inexperienced textual content messages was to purchase iPhones for family and friends members.

Beeper introduced a special strategy to messaging. Mr. Migicovsky created the corporate in 2020 to construct a single messaging app that might 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 provide an online app, making it troublesome to attach with its service. The one approach Beeper might combine iMessage was to route messages by means of Mac computer systems after which to an iPhone. The method delayed messages and made them much less safe.

As Beeper struggled with iMessage, an adolescent in Bethlehem, Pa., discovered an alternate resolution. James Gill, a 16-year-old pc 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 units.

“It wasn’t genius perception,” stated Mr. Gill, a junior at Saucon Valley Excessive College. “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 publish, he thought it might assist Beeper resolve its iMessage downside. He supplied Mr. Gill a job making $100 an hour, a serious improve 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 3 times, Mr. Migicovsky stated.

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

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

An Apple spokeswoman stated 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 stated in a press release.

Mr. Migicovsky disagrees. As an alternative of permitting Android clients to ship encrypted messages to iPhone clients, he stated, Apple is attempting to drive them to change unencrypted textual content messages. He has posted Beeper’s software program code on the internet and inspired Apple and cybersecurity consultants to assessment it.

Matthew Inexperienced, an affiliate professor of pc science at Johns Hopkins College, stated Apple had some authentic safety issues and warned that an prolonged struggle between the 2 firms might probably introduce vulnerabilities that criminals might exploit.

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

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

“This wasn’t our intention,” Mr. Migicovsky stated. “We’re attempting to make it work, inside our management, for the nice of the chat world.”