Magento - Gateway error Authorize.net - php

Question

Getting "Gateway error: Unable to read response or response is empty" when I try to post payments to authorize.net. Authorize.net cannot see anything coming through, host provider says no issues on their end.
I am using the Authorize.net payment type
I have verified my API login and trans ID in default, website, and store view
I have installed cURL SSL
I have verified no firewalls are blocking connections.
I am not in testmode
debugging is on, and results are below.
Below is the output from the exception.log file
2013-09-26T15:26:24+00:00 ERR (3):
exception 'Mage_Core_Exception' with message 'Gateway error: Unable to read response, or response is empty' in /app/Mage.php:595
Stack trace:
#0 /app/code/core/Mage/Paygate/Model/Authorizenet.php(1596): Mage::throwException('Gateway error: ...')
#1 /app/code/core/Mage/Paygate/Model/Authorizenet.php(594): Mage_Paygate_Model_Authorizenet->_postRequest(Object(Mage_Paygate_Model_Authorizenet_Request))
#2 /app/code/core/Mage/Paygate/Model/Authorizenet.php(436): Mage_Paygate_Model_Authorizenet->_place(Object(Strattas_Authnetcim_Model_Order_Payment), '44.53', 'AUTH_CAPTURE')
#3 /app/code/core/Mage/Sales/Model/Order/Payment.php(408): Mage_Paygate_Model_Authorizenet->capture(Object(Strattas_Authnetcim_Model_Order_Payment), '44.53')
#4 /app/code/core/Mage/Sales/Model/Order/Invoice.php(385): Mage_Sales_Model_Order_Payment->capture(Object(Mage_Sales_Model_Order_Invoice))
#5 /app/code/core/Mage/Sales/Model/Order/Payment.php(569): Mage_Sales_Model_Order_Invoice->capture()
#6 /app/code/core/Mage/Sales/Model/Order/Payment.php(375): Mage_Sales_Model_Order_Payment->_invoice()
#7 /home/morrell/public_html/app/code/core/Mage/Sales/Model/Order/Payment.php(317): Mage_Sales_Model_Order_Payment->capture(NULL)
#8 /app/code/core/Mage/Sales/Model/Order.php(877): Mage_Sales_Model_Order_Payment->place()
#9 /app/code/core/Mage/Sales/Model/Order.php(1406): Mage_Sales_Model_Order->_placePayment()
#10 [internal function]: Mage_Sales_Model_Order->place()
#11 /app/code/core/Mage/Core/Model/Resource/Transaction.php(105): call_user_func(Array)
#12 /app/code/core/Mage/Core/Model/Resource/Transaction.php(159): Mage_Core_Model_Resource_Transaction->_runCallbacks()
#13 /app/code/core/Mage/Sales/Model/Service/Quote.php(189): Mage_Core_Model_Resource_Transaction->save()
#14 /app/code/core/Mage/Sales/Model/Service/Quote.php(249): Mage_Sales_Model_Service_Quote->submitOrder()
#15 /home/morrell/public_html/app/code/core/Mage/Checkout/Model/Type/Onepage.php(777): Mage_Sales_Model_Service_Quote->submitAll()
#16 /app/code/core/Mage/Checkout/controllers/OnepageController.php(567): Mage_Checkout_Model_Type_Onepage->saveOrder()
#17 /app/code/core/Mage/Core/Controller/Varien/Action.php(419): Mage_Checkout_OnepageController->saveOrderAction()
#18 /home/morrell/public_html/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(250): Mage_Core_Controller_Varien_Action->dispatch('saveOrder')
#19 /app/code/core/Mage/Core/Controller/Varien/Front.php(176): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#20 /app/code/core/Mage/Core/Model/App.php(354): Mage_Core_Controller_Varien_Front->dispatch()
#21 /app/Mage.php(687): Mage_Core_Model_App->run(Array)
#22 /index.php(87): Mage::run('', 'store')
#23 {main}

Answer 1

i think you enabled Test Mode in System->Configuration->PaymentMethods

Answer 2

Turns out there was an issue with my nameservers at my host. I figured this out using information here: http://www.magentocommerce.com/boards/viewthread/50611/ (the referenced thread can be viewed in the internet archive, here https://web.archive.org/web/20150315055800/http://www.magentocommerce.com/boards/viewthread/50611 )
After that I received an error message associated with a blocked IP. I added my new ip at accounts.authorize.net in Tools (top menu) > Fraud Suite (left menu) > Authorized AIM ip addresses (body, second to last item).