AT&T says it will record $10 billion in charges in its fourth quarter.
This includes a $7.9 billion pretax loss related to accounting adjustments for gains and losses on pension and benefit plans.
AT&T is also recording a $2.1 billion non-cash charge as it abandons some copper used for landlines.
AT&T said Friday that the copper, which was typically used for wiring, is not needed as consumer demand declines for its older voice and data services. The need for many copper landlines is disappearing as consumers opt for cellphones and Internet-based phone service that arrives over cable TV and fiber optic wiring.
Dallas-based AT&T Inc. wants to turn off its copper landline network by the end of the decade.
AT&T stock slipped 40 cents to $33.40 in extended trading.