Cleaned up code

Improved the readability by using real type params
instead of passing async result into the handling methods.

Test: Telephony sanity tests + unit tests
Bug: 73659459

Merged-In: I776f3ac21106793b65820a2fe92ef6de52f243ca
Change-Id: I776f3ac21106793b65820a2fe92ef6de52f243ca
(cherry picked from commit 2752f53b)