Hi,
unfortunately there isn't, although you can log all users off after a period of the user being logged in. If you go to system -> service parameters -> the extension mobility service, you can set this behaviour.
On the other hand, I've not seen any problems with CTI applications in this scenario, as usually when you close the IP phone, it doesn't leave you logged in. You can confirm if this is the case using the actively logged in device report on the devices screen.
One other way round this might be to not use extension mobility on softphones but set up an individual softphone for each user.
Thanks,
Chris