Shane Bauer and Josh Fattal have been held in Evin Prison in Tehran for more than a year. The two men and Sarah Shourd were arrested on espionage charges in 2009 after straying into Iran while hiking in Iraqi Kurdistan.
Iran freed Shourd on humanitarian grounds in September.
"We were relieved to speak to Shane and Josh, particularly during the Thanksgiving holiday. We hope that their calls home bode well for their release on humanitarian grounds during this holiday season," the families said in a statement to CNN.
"They are able to spend significantly less time outside their cell in the prison yard each day and have not received the books we send them," the families said. "We are deeply concerned about their increased isolation and trust that these restrictions will be reversed."
The hikers said they knew nothing about the proceedings against them or why their case is taking so long to resolve.