I found one error. When I copied your Ruby script, I missed the second "end". I added it and tried again, but now I had another error:
DialPlan 02:17:27:791 sip1(6116): Using dialplan dialplan for Out call to sip:803xxxxxxx@sipsorcery.com.
NewCall 02:17:27:806 sip1(6116): Executing script dial plan for call to 803xxxxxxx.
DialPlan 02:17:27:853 sip1(6116): Phone Number 803xxxxxxx
DialPlan 02:17:27:853 sip1(6116): SDP on GoogleVoiceCall call had public IP not mangled, RTP socket xxx.53.114.116:16802.
DialPlan 02:17:27:853 sip1(6116): UAS call progressing with Ringing.
DialPlan 02:17:27:853 sip1(6116): Logging into
google.com for user.
DialPlan 02:17:27:884 sip1(6116): Google Voice pre-login page loaded successfully.
DialPlan 02:17:27:900 sip1(6116): GALX key G0q9gKFG5H0 successfully retrieved.
DialPlan 02:17:28:494 sip1(6116): Google Voice home page loaded successfully.
DialPlan 02:17:28:509 sip1(6116): Could not find _rnr_se key on your Google Voice account page, callback cannot proceed.
DialPlan 02:17:28:509 sip1(6116): Exception on GoogleVoiceCall. Could not find _rnr_se key on your Google Voice account page, callback cannot proceed.
DialPlan 02:17:28:509 sip1(6116): Dialplan cleanup for user.
DialPlan 02:17:28:837 sip1(6116): Dial plan execution completed without answering and with no last failure status.
DialPlan 02:17:28:837 sip1(6116): UAS call failed with a response status of 480.
Here 803xxxxxxx is the number I was trying to dial, but I have no clue what "_rnr_se key on your Google Voice account page" means.