Calero made his debut for Nicaragua in an April 2001 friendly match against Belize and has, as of December 2013, earned a total of 26 caps, scoring 4 goals. He has represented his country in 2 FIFA World Cup qualification matches and played at the 2001, 2003, 2005 and 2011 UNCAF Nations Cups as well as at the 2009 CONCACAF Gold Cup.