'Severe' VoIP Bug in iOS 4.2 Golden Master? [Update: Fixed in iOS 4.2.1]

Toktumi, the firm behind the popular Line2 VoIP application for iOS devices, today sent an email to its customers warning them of a bug in iOS 4.2 that results in the ringer continuing to ring even after a call is answered when Line2 is running in the background. According to Toktumi, Apple's engineers are aware of the issue, which reportedly affects all VoIP applications, and have classified it as "severe".

Attention all Line2 iPhone, iPod Touch, and iPad users:

Please do not upgrade to iOS version 4.2.

If you upgrade to iOS 4.2 and you are running Line2 in the background, the ringer will continue to ring even after an incoming call is answered. This affects Line2 as well as all other VoIP and social calling apps. (Note: If you do not use Line2 your Toktumi service will not be effected.)

Apple Developer Support is aware of this issue and has designated its status as 'severe'. However, as of the most recent iOS beta (GMSeed build), this issue is still not resolved. We apologize for this inconvenience and will update you as soon as we get more information from Apple.

Line2 will continue to work as normal with your current operating system. We strongly encourage you not to install iOS 4.2 until Apple fixes the upgrade issue. We will send out an email update as soon as it is safe to upgrade.

Sincerely,
The Toktumi/Line2 Team

Apple released a golden master version of iOS 4.2 to developers on November 1st, and a public release was expected last week. Reported issues with Wi-Fi connectivity on the iPad have been blamed for delays from Apple's original internal timeline and resulted in Apple pushing out a revised golden master build for the iPad late last week.

Update: It is not yet known if the issue is addressed in the iOS 4.2.1 golden master that was just seeded to developers.

Update 2: One beta tester has informed us that this bug is indeed fixed in the new iOS 4.2.1 seed.