Patent Watch Online provides patent monitoring services for applications in the

• USPTO Public PAIR system,
• European Patent Office (EPO), and 
• World Intellectual Property Organization (WIPO) PCT system.
  

Process

1. You provide us with the patent applications that you would like us to monitor.
2. Choose whether or not you’d like to receive status reports once or twice a month.
3. We will let you know of any changes in the status of the patent application, whether an office action has been issues, or a simple letter.
4. We will send by email an alert of the change of status along with a copy of the letter or office action.

Check out a detailed explanation here.