Bell South's phone lines could be used not only for making calls but also for dial-up internet access.
The Information Superhighway plan had not yet been formally proposed, and apart from the NSFnet's main backbone using optical fiber communications, the other branches still relied on traditional phone lines.
Therefore, if the network interconnection plan were to be implemented, then Bell South's telephone network would have another field to play in.
Providing data connectivity services for the network wouldn't conflict with Bell South's telephony business and could even bring in additional revenue.
Moreover, the prospects of the network communication market were much larger than IP telephony. Capturing just a small part of it could bring enormous profits to Bell South.
It was precisely because of this potential that Duane gave up the 5 million US Dollar patent fee and instead chose the network interconnection plan.