Southwest Rapid Rewards - Why no partnership with traditional phone companies?

I find this part of Rapid Rewards severely lacking.

MCI used to be a partner. I think you can blame the frequent overhauls in that industry.

MCI used to be a partner. I think you can blame the frequent overhauls in that industry.

MCI still partners with NW.
Sprint partners with US.
WN needs a partner.

MCI still partners with NW.
Sprint partners with US.
WN needs a partner.

WN doesn't need a partner, but it would be nice if there were more partners to help earn more credits. :)