While trying to figure out the polite imperative form of 呼ぶ I figured the correct conjugation to be 呼んで下さい。I found instead that, colloquially, the imperative is 呼び出して下さい。 Am I correct in assuming that this is to distinguish between, 読んで and 呼んで in everyday speech?
No. As 読んで and 呼んで have different accents in both standard Japanese and Kansai dialect.
呼ぶ and 呼び出す are...
- 呼ぶ: call someone.
- 呼び出す: call someone and ask him to come somewhere.
They are similar, sometimes same.
If my understanding about your question, which is, you are thinking Japanese are --differentiating-- the intonation on purpose in order to distinguish the meaning of the 2 verbs, 読む, 呼ぶ, I think my answer would be "Please remember so...".
There are 2 ways of pronouncing Kanjis, which are 音読み（Onyomi) and 訓読み(Kunyomi).
Now, 訓読み is the Japanese way of reading --original way of Chinese ( meaning, the "real" Chinese do not pronounce such ).
The 2 verbs, 読む(Yomu), 呼ぶ（Yobu) has both 訓読み respectively.
And we do not ordinarily "write" or "say" 呼む.
「読み-て」 ヨミテ ( Yomite ) → ヨンデ ( Yonde )「読んで」
「呼び-て」 ヨビテ ( Yobite ) → ヨンデ ( Yonde )「呼んで」
So, the "basic form" of the each verb is different. 読む（Yomu), 呼ぶ（Yobu), respectively.
Thus, if I am asked if Japanese is trying to differentiate the pronunciation, I would like to answer "because the "basic form" is different...".
For your further information, here is the Japanese "accent" of ( especially ) Japanese verbs, nouns, ..
If you click よ button，then you can find how to pronounce the 2 verbs. ( I am afraid I can not copy and past the up and down red lines but you can certainly find there. )
Have a good day.