Symptom:
When setting up the SSL VPN to ASA using phone's built in VPN client, it is required to set the "Alternate TFTP" setting to "yes" and configure the TFTP server IP in the next entry in the IP phone Network configuration menu. Without explicitly setting this, the Cisco IP Phone will not be able to contact the TFTP server and download its configuration and other files and function properly. IP phone administration guides do not state this requirement.

A common symptom of not having alternate TFTP configured on a VPN connected phone is that the phone will not log missed, placed, or received calls.  After configuring an alternate TFTP, missed, placed, and received calls log properly under the phone's call history.

Conditions:
All IP phones supporting SSL VPN with their built in VPN client that are not provided the correct TFTP address via OPTION 150 from local DHCP server.