Telco worker here. These sort of exchanges in big cities are usually built from solid concrete to minimise damage from these sort of attacks - either from warfare or terrorism. At least, for buildings built during the world wars or cold war.
Here's an exchange in Melbourne: https://1.bp.blogspot.com/-gHeHncO6W4U/ThpRVvEhXHI/AAAAAAAAJ...
Built with solid concrete and with thin windows.