Hi,
Can you share brief details about your environment ? Are you using on-premise Call-Maneger in your office ? IP addresses for your call-manager are reachable through home ?
Also, when you connect phone at home, did you define IP Addressess statically or getting through DHCP ? If DHCP, then did you add option 150 in the DHCP settings which define ip address of your Call-Manager/Communications Manager ?