Eric Migicovsky, co-founder of the all-in-one messaging service Beeper, says Beeper Mini can do this because iMessage has been reverse-engineered. The script worked, so Beeper hired the researcher and, over the last three months, completely rewrote their client into this new Mini app. At the moment, Beeper Mini supports group chats, high-resolution images and video and voice messages, stickers and GIFs, reply threads, and sent/delivered/read/typing status.

Source: Beeper Mini for Android sends and receives iMessages, no Mac server required

Curious about which way this goes