Lumen is technically one of the spinoff RBOC (having incorporated Qwest which was the RBOC successor to US West).
Lumen also includes the former Century Telephone which was not a Bell member.
As you know, of the seven RBOC (like the seven dwarfs), two are now Verizon and four are now the reborn AT&T, so Lumen was the odd man out.
Lumen has not been big in cellular, and their local landline areas are pretty stagnant. Lumen already sold off local landline exchanges in 20 states to Brightspeed which is a new company.
It may be that fiber is their biggest remaining asset…?
If Lumen sells fiber (etc) to AT&T:
1) It’s getting close to the final act of the former Bell System re-monstering into just the two big players, Verizon and AT&T/2.0
2) From Lumen’s POV, it may be not so much a sale of assets, but rather a merger into AT&T. Because as I said, what remains of Lumen afterward may be a “Rump state”.
https://en.wikipedia.org/wiki/Rump_state