Are you sure that the DHCP server on the remote side is providing option 150?
Would the freepbx distro asterisk 1.8 be a better idea? So I would just use a cut down one if you are uploading firmware to the phone.
I have the following problems with a new communication manager 7.1.3The IP phones 7970, 7911, 7906 send the messages "Error updating locale" eventhough the local installer hasalready been loaded. The default user locale option is spanish but the softkeys are shown in english.
If we try to restore the phones to the factory default values the phones blocked and we can not access to them, the olnymessage displayed is upgrading (7911 model) the 7970 model just display the cisco'logo.
Is the phone doing the VPN itself (I don't think those model phones support this), or is the VPN terminating on firewalls/routers?
Do you have option 150 for TFTP set on the phones, either manually or by whatever is serving DHCP at the remote site?