Dear teacher,

I understand preposition "in" has the meaning of during a period of time.
for example:

1. I phoned you in the morning.

I also understand preposition "on" has the meaning of indicating when sth happens. for example:

2. My birthday is on Tuesday.

I also know I must use "on" in the sentence below.

3. I phoned you on Tuesday morning.

Can I say "I phoned you in Tuesday morning." because I phoned you really during Tuesday morning.

(really during the part of that period.)

I am much obliged to you for your help.

Thanks.