The pronunciation pattern of phrasal verbs is less complicated than the grammar. Phrasal verbs have a stable, predictable stress pattern, which is: the 2nd word gets the stress. That means that the 2nd part is said more strongly (or, it sounds louder, longer and higher).
hang ON to
look UP to
drop IN on
This stress pattern holds true whether the phrasal verb is un-separated, or when separated by just one or by several words.
They called OFF the meeting.
They called it OFF.
They called all of the remaining sessions OFF.
Listening for the stress can help you distinguish between a normal preposition and a phrasal verb. Prepositions are normally weak, unstressed words in a sentence, but as part of a phrasal verb, they are stressed clearly. The following two sentences show the difference.
We turned on the wrong street.
In this sentence “on” is a preposition. It is pronounced weakly and can be hard to hear because prepositions are not normally stressed.
We turned on all the lights.
In this sentence “on” is part of a phrasal verb. It is strong and easy to hear because the second word of phrasal verbs do receive stress.
When speaking it is important to say phrasal verb stress correctly because you could accidentally say something you didn’t intend. Let’s use the sentence “I ran into the store” for an example. The meaning will be different if you change the stress pattern.
“Into” as a preposition
As a preposition, “into” should be unstressed, and the words “ran” and “store” are both strongly stressed, which gives: I ran into the store. You would say it this way if you were in a hurry or if you wanted to get out of the rain.
“Into” as part of a phrasal verb
As part of a phrasal verb, “into” should be stressed, making “into” and “store” the two strongest words in the sentence. That would give: I ran into the store. Now, I hope that you don’t ever need to say it that way, because that would mean that you crashed — if you walked without looking where you were going, or if you had a driving accident and hit the store with a car.
So, the good news is, knowing about the stress pattern of phrasal verbs can help you improve your pronunciation, and also help you with figuring out a little bit of grammar.
(There are so many phrasal verbs in English that it might help to study them a bit — here are some books that I would recommend.)