Re: Divert
This was a popular scam by some employees - divert their landline DDI to a family/friend number in a high cost overseas location. On a BT Monarch based PBX *21* had to be entered on the handset itself - so one diverted number per weekend.
On some Mitel SX2000s you could call your voicemail from outside and change the forwarding on the fly. So calls to all your family and friends overseas.
There were really only a couple of countries that showed up on the call logger and this was almost expected behaviour by some groups of employees, I'm sorry to say.
Not such a problem now, as every site I manage now has UK premium rate/DQ blocked and overseas calls with a certain > per minute charge blocked too.