The move was made in response to the attacks at Brussels’ international airport and in one of the city’s subway stations that left at least 30 people dead. The Islamic State has already claimed responsibility.

AT&T (T), Verizon (VZ), and Sprint (S) are all crediting their customers for calls and texts made to and from friends and family in Belgium as have Boost Mobile and Virgin Mobile USA. Sprint, Boost Mobile and Virgin Mobile USA have waived their fees until March 31, AT&T is waiving fees until March 28, and Verizon Wireless users won’t face fees on March 22 and March 23.

For more about the Brussels attacks, watch:

It’s common for carriers to credit customers in the wake of natural disasters and terrorist attacks. Following the terrorist attacks in Paris in November 2015, AT&T, Verizon, Sprint and T-Mobile all offered free calls and texts to and from France.

Travel site Airbnb has also waived fees for those affected by the disaster and checking in to homes this week.