Adding additional IPs with MTS is done by purchasing a framed route. The minimum size is 6 IP addresses for $9.95/month. Pretty good if you need an extra IP or two as our client did. The description of the service is here:
MTS provides the following document to clients:
We did the install for a Pace modem. So, the screenshots below show what needs to be configured for that specific modem type.
After you have connected to your Pace modem, go to Settings > Broadband > Link Configuration.
At the bottom of this page, in the Supplementary Network section, select Enable to add an additional network.
You should also select the Auto Firewall Open option to automatically forward all Internet traffic to hosts inside the Pace box. If you don't, you'll need to either forward specific ports in the Pace firewall, or configure additional DMZ zones in the Pace box. In our case, we were configuring a firewall behind the Pace box and wanted all traffic to be forwarded.