josh_marchant,
The best way to handle this is to setup Teleworker on your system and then have the users take their IP phones home with them. If you don't have IP Phones then this becomes an expensive proposition.
To get IP Phones requires you to buy a phone and a license. You could use softphones but that would still require you to purchase a license for the phone and reduce the feature set and functionality that your users are used to.
You would also need 1 or 2, depending on your hardware, Public IP addresses pointed to the MiVO-250 for this to work.
Thanks,
TE