Hello,
Personally, I do not call ahead, unless I ordered the coins and I want to be sure they arrived. I live in a metropolition area. There are 100's of bank branches with in a 20 mile radius (maybe 10 mile radius). I belong to two banks and a credit union. Most will order coins for me. Sometimes at a few branches they start to get tired of walking to vault and getting the coins. They would prefer to just sit there all day and eat doughnuts for lunch!

They may say, do you have a commerical account, or we might have to start charging you. If I skip that branch for a while, then come back a month or so later I start the cycle again. This is only if I am getting good coins there.
It is worth it to just drive around and hit every single bank you see. Many tellers dont even know what a silver coin is, or even the coin. One bank charged me a dollar apiece for Kennedy 50 cent coins. Of course, I pointed out that it says half dollar right on it. Just gettting what they have in their tray or personal safe at their feet is good. I have got entire rolls of silver this way. Many tellers are friendly great people. There are a number of banks, that have ordered me boxes and I am not even a member. Of course, if they ask, I am a member.
You will be surprised how many people roll search halves. Many will have boxes, that they will not give you, as someone had ordered them. One time I went to a bank out of my area. They had a few hundred dollars worth. I was thinking Sweet!

Then this old guy about a 100, at the next window shouts to the teller, THOSE ARE N'T NEW ARE THEY. The teller turns to him and says, no we searched them and pulled out the silver for you!

Well, I passed on those.
Searcher