We recently started noticing that a certain floor of a building on campus can only call 1 direction. When either side tries to call the one side in the bottom of our building cannot hear anything that the other side is saying. This only happens to the 3905's on the first floor of a specific building. If you use a higher model phone on that floor it doesnt happen and if you bring a 3905 up a floor or anywhere else and it functions perfectly. Strangely, this isn't consistent as some 3905 phones on that floor can call some phones in other areas of the building and there are no problems at all. I am stumped. Any suggestions would be appreciated!
Phone system is Cisco
Switches are Cisco 2960S-48fps-L models with IOS 15
Call Manager and Unity versions are 11.5.1
Phone affected on the first floor of the one building are Cisco 3905's
If any log files are needed I can provide those.