The company makes it a point of logging as little information as possible. For example, it logs IP addresses used by users to log in and these are kept for 7 days, but there are plans to reduce retention time to 24 hours.
"There are lot of logs that we don't keep at all," Callas said. "For example, we don't keep logs about who is calling who."
By not logging many things sometimes it's actually hard to debug the company's network, Callas said. There's internal debate about that and how to strike a balance, he said. "We need to run our network, but at the same time we don't want to know what you're doing."
Silent Circle hopes that its services will be particularly helpful for political and human rights activists in countries where free speech is not well protected.
But at the same time, since everything is encrypted and decrypted between the client devices and there are very few logs kept, there are concerns that the service could be abused by criminals to hinder the ability of law enforcement agencies to investigate their activities.
"We have a terms of service that says there are things that we don't want people to do," Callas said. "We don't want people to use it for criminal purposes, but we also understand that it's illegal to be an activist in an oppressive country."
"We have a fine line to walk and obviously there are certain things that we consider to be a violation of the terms of service and some things that we don't consider to be a violation of the terms of service," Callas said. "There's a lot of activist activity that might be technically illegal in some country that we don't actually care about, but there are other things that obviously we do care about. We handle this as best we can."