Answer:
At midday. In a 24 hours clock, 12:00, in a midday format 12 PM.
Explanation:
In order to calculate this you just have to withdraw the hour difference between both the Eastern Standar Time and the Pacific Standar Time, which normally are 3 hours of difference, since he is in the Eastern Standar Time, that means he is 3 hours ahead of you, so in order to calculate the hour at which you should expect the call, you have to withdraw 3 hours frmo 3 P.M which would make it midday or 12 P.M