There will be a bit more drain while on a call, but not terribly so, especially if the screen will go black while on the call.
It has more to do with how weak the signal is from the tower to your phone.
The weaker the signal, the more power your phone has to transmit to make up for the "bad signal path".
It may be, that in your location, you are experiencing a bad signal location.
Is your experience all the time, or just some of the time?
Aside from the above, batteries are sensitive to how you use them. If you have a habit of using it up completely and then recharging it, the battery will not last you very well. Lithium-Ion batteries prefer to be in a "good state of charge", the manufacturers recommend recharging at the 40% level.
Also, if the battery is drained all the way to 10% or less, and you charge it non-stop until it is fully recharged, that also damages the battery. Why? because it will get too hot.
I make it a habit to recharge in stages, if at 50% or more, I let it charge all the way. If lower than 40%, I do it in two stages, keep the battery relatively cool, and it will last you forever.
I have a Galaxy S phone that is 6+ years old, and the OEM battery is still quite good.