Apple finally acknowledged a bug within its iMessage system preventing some users from receiving text messages when they moved from an iPhone to another type of mobile, promising to fix it in a future update.

iMessage enables smooth communication between various Apple devices such as iPhone, iPad, and Mac, with messages routed through Apple’s servers rather than being sent through the wireless carriers as a standard text message.

"We recently fixed a server-side iMessage bug which was causing an issue for some users, and we have an additional bug fix in a future software update. For users still experiencing an issue, please contact AppleCare," Apple told Re/code.

The problem arises if someone switches to an Android or Windows phone from an iPhone while keeping the same number, with the new phone still being recognised by the Apple’s messaging system as an iPhone.

Although this can be rectified by switching off iMessage, for some users the problem persists, especially if they are not able to dissociate their phone numbers from iMessage. Messages sent to them by friends disappear into Apple’s database instead of being passed along as a traditional SMS message

Backlash against the bug is growing with a user in California filing a lawsuit against Apple last week, seeking class-action status. The suit claims that the tech giant’s actions violate California’s unfair competition law and also interfere with a wireless carrier’s abilities to deliver promised service to consumers. Apple has not commented on the lawsuit.