If you travel (even if you do not), Skype is your friend. It is either free or close to free for almost all calling and is available anywhere there is WiFi. There are alternatives to Skype, but I find this to be reliable and easy.

For what it is worth, I consider it absurd in this day and age that BA is unable to provide local calling with internal call direction from any location it serves. E.g., a cost-free means to reach BA and then a means to have your call directed to the appropriate person ("push 1 for reservations, push 2 for BAEC, push 3 for...." The technology to accomplish this is decades old and cheap.