I saw in an Documentation say that URL above you posted seems different see below
View post on imgur.com
Well i have a solution for you Based on this documentation i used this plugin and i just changed line no 46 to
$this->merchantone_liveurl = 'https://secure.networkmerchants.com/api/transact.php';
and used http://i.imgur.com/wugQRIW.png for settings i got a succesful transaction
SUCCESSon 21-02-2016 04:25:41 UTC with Transaction ID = 3005963951 using sale, Authorization Code =123456,Response Code =100, Response =1
Hi, thank you for your efforts in this. Unfortunately it still does not work. I’m not sure why but it does not.
I tried the above changes with both the NMI API logon and transaction key
and that failed. The I tried again using the NMI username and password and that did not work. Then I double checked with my host to insure that cURL is both activated and working, which it is and still no luck.
In my opinion, this is a big weakness of Woocommerce. I set up NMI with Bigcommerce in 5min and it worked right from the start.
I give up.
Thank you again for your time.
The Solution that finally worked was to use NMI ( network merchant Inc) username as api login id and NMI password as API key
We tried using API login and Key but it never worked till we used NMI username and password as API login and Transaction key
and also changing line no 46 for merchantone addon to following
$this->merchantone_liveurl = 'https://secure.nmi.com/api/transact.php';
