Are your contacts in your Gmail account - both PC and the X?
If they are on one but not the other, you need to set up the sync so everything is coordinated between the two. Two places need to be activated:
Settings > Data Manager > Data Delivery > checks by each option
Settings > Accounts > your Gmail account > checks by Sync Contacts, Sync Gmail and Sync Calendar
Then, all will stay instantly synced whenever you make changes either on your PC or X. This should take care of the ID when calls are received/made.
PS - You can manually sync at any time after these settings are made by going back into Settings > Accounts > Gmail > Menu > Sync now