AT&T, Sprint and Verizon have all announced that customers in the U.S. can call and text numbers in Belgium free of charge for a number of days in the wake of attacks in that country today.

AT&T stated:

Our thoughts are with the people of Belgium and our customers who have friends and family there. We're going to credit our wireline and wireless customers for all calls and text messages to Belgium from March 22-28."

Sprint's CEO Marcelo Claure used his Twitter feed to announced the carrier's plans:

Verizon's free calling offer also includes Turkey, which experienced its own attacks a few days ago:

Wireless users will incur no charges for texts or international long distance calls originating from the U.S. to Belgium on March 22 and 23, 2016, and from the U.S. to Turkey from March 19 and 20, 2016 (applicable taxes and surcharges will apply). Home wireline telephone customers will incur no charges to Belgium from their U.S. landlines on March 22 and 23, 2016, and from the U.S. to Turkey on March 19 and 20, 2016 (applicable taxes and surcharges will apply).

Update: T-Mobile is also offering free calls to both Belgium and Turkey:

The offer applies to all T-Mobile Simple Choice postpaid customers. It is effective from Tuesday, March 22 through Friday, March 25, 2016 for Belgium, and from Saturday, March 19 through Tuesday, March 22 for Turkey. Customers will see regular charges on their bills with corresponding credits.