Use 'Call forwarding' instead of 'Call diversion'
'Call forwarding' is a far more common term in United States English than 'call diversion.'
Maybe BT uses the 'call diversion' term so that's why it was used in the spec?
Even the en-GB localization of Android uses 'call forwarding' for this feature.
Google Trends shows that Australia & UK residents search for 'call diversion' a lot but not quite as much as for 'call forwarding'. You can "zoom in" on specific countries by using the "Limit to" filter on the left.
DistroRelease: Ubuntu 13.10
Uname: Linux 3.10.0-5-generic x86_64
Date: Fri Jul 26 16:08:47 2013
InstallationDate: Installed on 2013-06-14 (42 days ago)
InstallationMedia: Ubuntu-GNOME 13.10 "Saucy Salamander" - Alpha amd64 (20130613)
UpgradeStatus: No upgrade log present (probably fresh install)