Leaving a voicemail for oneself

This an odd one.

We are 100% SfB online

From time to time a user will be driving into work and want to leave a voicemail for themselves, as a reminder when they get in. This used to work in the past, however now they get a message saying "This feature is not currently available"

Seems related to Skype resolving their mobile number to their contact and then is calling them-self. When the you should get transferred to voicemail you get the error.

Anyone have any ideas?

Thanks

LT