There does not seem to be any access to NBC. Why not. It is a major network.
If you're referring to the channel on Optik TV itself, NBC is part of the essentials package.
If you're referring to online content. You'll find that nearly all US networks won't allow Canadians access to their content. The one exception I know of is A&E through their iOS / Android app.
Most of the content from the various American channels is licensed through one of the Canadian networks. You'll have to figre out which one and stream it from their website instead.