If you want to use command line to send sms with port-2.X, you should access the second board system,
There are two RJ45 network ports, ETH1 and ETH2. If you choose ETH1, you should access board 1, and then access board 2 to send sms. If you choose ETH2, you can access board 2 directly to send sms.
Do you use AMI interface to send sms? you can use the same ip and different port (5038, 5039)
And you can try to use http interface to send sms, it is a easy way to send sms, here is the http interface manual: