The old method of authentication to Google Voice accounts, using a stored password, is obsolete, is not approved by Google, and it is a security exposure. That's the method you are still using on your SP1. You need to delete that SP configuration entirely. You can then save your OBi's configuration to an XML file, using the local web page interface.
Log into the device's IP address. Go to System Management, Device Update, and the Backup Configuration section. Click the "Use OBi Version" box, and then take the backup.
Upgrade the firmware.
Factory-reset your device, add it to the OBiTALK dashboard, if not already there, and then configure SP1 and/or SP2 with Google Voice as you wish.
After verifying that it works, you can use the local interface to restore your configuration again. The backup does not contain passwords and will not overwrite the GV credentials.
If anything in your saved and restored backup breaks some function in the current firmware, you will need to factory-reset it again, and then modify your custom settings individually.