I guess your phone is locked to your Network.That's why your phone asking the unlock code.you can get the unlock code for your phone from you Network service provider or any third party online vendors like http://www.simpleunlocking.com/alcatel-ot-s107/rs16wp9/ here you need to specify your current Network name,IMEI number of your phone.Then they deliver unlock code to you through mail.And you can get free unlocking instructions from the site http://www.mobileunlockguide.com/alcatel-ot-s107 using this unlocking instructions you can unlock your phone easily.
sahana
September 2013