2.3.13.3 Fine-Grained Initialization Sequence
Other than basic startup, shutdown, and capability query operations as shown above, all operations related to phones are done strictly within the Open/Close pair as shown below:
Phone operations within the Open/Close pair are shown. The Service Provider may choose to do these synchronously or asynchronously. If an operation completes asynchronously, another operation may be requested before the first reports completion. Thus operations can overlap in any way. The Service Provider must eventually report completion for any operation requested. Closing the phone forces outstanding operations to complete (possibly with a "failure" indication).