Capital spending among service providers may decrease by more than 10% next year, potentially crimping the sales of major vendors, according to investment firm UBS. Overall spending this year is up 5% to 10% from 2007.

AT&T's wireline spending in the United States could be down by that much, which would blow away UBS's earlier estimate of a 4% drop, the firm stated this week in a bulletin to investors. UBS believes other carriers may also cut "non-strategic" wireline spending next year, bringing overall expenditures down 10% or more vs. earlier estimates of a 3% drop.

An example of non-strategic wireline spending is investment in video, according to UBS. This could affect both consumer and business video products from such major vendors as Cisco, HP, Polycom and Tandberg.

Wireless spending is holding up better for next year, UBS says, but could still be down 7%."We currently do not see a downside to this estimate, especially with the continued increased penetration of smartphones that will likely increase data usage," UBS analyst Nikos Theodosopoulos stated in the bulletin.

U.S. cable capital spending could be down by 5% to 10%, the firm states.