After mocking and pleading with Apple Inc. (AAPL  ) to open up iMessage to non-iPhone users, Alphabet Inc.'s (GOOG  ) (GOOGL  ) Google is now knocking on the doors of European Union regulators.

What Happened: Google has partnered with several European telecom companies, including Vodafone Group Plc. (VOD  ), Deutsche Telekom AG. (DTEGF  ), and Orange to urge the European Commission to recognize Apple's iMessage as a "core" service, reported The Financial Times.

Doing so would force Apple to make iMessage interoperable with other messaging services.

The letter was written amidst an ongoing EC investigation to determine if iMessage meets the stringent criteria to fall under the purview of the DMA. Google has been outspoken in its support for Apple to adopt RCS, a universal messaging standard.

The group argues that iMessage meets the benchmarks for a core platform service under the DMA, as it is run by a company with yearly revenues surpassing €7.5 billion and boasts over 10,000 monthly active business users in the EU.

On the other hand, Apple maintains that the iMessage app is primarily developed and promoted for individual consumer communications. The tech titan also asserts that iMessage is not popular enough within the EU to merit designation as a core platform service.

The EC's investigation is ongoing, with a decision anticipated before February of the coming year.

Why It Matters: This development follows earlier efforts by Apple to prevent its services from being classified as "gatekeepers" under the EU's forthcoming DMA.

Apple, along with Microsoft Corp. (MSFT  ), were reportedly lobbying to exempt their services, including iMessage, from this designation.

The DMA is aimed at promoting competition and interoperability among tech giants. As the EC continues its investigations, the implications of these classifications on tech companies and their services will be closely watched.