After you disable the simultaneously ring or call forwarding feature in TTU Unified Communications for a mobile phone number, you continue to receive these incoming calls on your mobile phone. This occurs regardless of whether the Skype for Business app is actually installed on your mobile phone.

When you install the Skype for Business mobile app, you're prompted to provide your mobile telephone number during the app setup process. When you do this, a static registration with a unique endpoint ID is created on the Skype for Business front end server for that specific mobile device. If the Skype for Business mobile app was deleted from the mobile device without first signing out of the app, the static registration for this specific mobile device will become orphaned on the front end server.

Skype for Business calls will continue to be directed to the mobile device's phone number and any phone number that you provided when you set up the Skype for Business mobile app. The forwarding will occur for a 15-day expiration timeout period from the last sign-in using the Skype for Business mobile app.

NOTE: The 15-day expiration timeout period's call forwarding and simultaneous ring settings are independent from the settings for call forwarding and simultaneous ring in the Skype for Business desktop app. The settings cannot be disabled from anywhere other than the Skype for Business mobile app on the specific mobile device by signing out of the Skype for Business mobile app.

If you have the Skype for Business app installed on the mobile device

To resolve the problem, sign out of the Skype for Business mobile app on the specific mobile device. When you sign out of the Skype for Business app on a specific mobile device, the static registration for the mobile device is removed from the Skype for Business front end server. After the static registration is removed, Skype for Business calls will no longer be sent to the mobile device.

If you do not have the Skype for Business app installed on the mobile device

To resolve the problem, re-install the Skype for Business app on the same mobile device where you were signed in before, set up the app for TTU Unified Communications, and then sign out of the Skype for Business app. When you sign out of the Skype for Business app on a specific mobile device, the static registration for the mobile device is removed from the Skype for Business front end server. After the static registration is removed, Skype for Business calls will no longer be sent to the mobile device.

If you cannot sign out of the Skype for Business app on the specific mobile device that was used to create the current static registration, you have to wait the 15-day expiration timeout period before calls will stop being directed to the mobile phone number.

NOTE: Adding another phone number on a Skype for Business mobile app won't remove an orphaned static registration and therefore won't stop calls from being sent to the mobile device. The only resolution is following the methods described above.