When I hear the term testing phases, I think of the following:
1. Unit Testing
2. System Testing
3. Integration Testing
4. User Acceptance Testing (UAT)
However, that being said - testing begins when the project begins and ends when the project completes:
1. Planning the tests that you will execute
2. Executing said tests
3. Reporting the results that were observed during the tests.
4. Completing all tests, appropriate paper work, and releasing the software.