Cisco Systems’ growing Voice over Internet Protocol services is adding a new degree of security.

The CallManager 4.1 product includes encryption protecting voice calls and voice mails through Cisco Unity, an encrypted messaging feature that Cisco said is an industry first. The product is for new model phones and is available as a update for more than 2.5 existing, installed VoIP model phones, Cisco said.

“Media encryption helps to ensure the security and privacy of telephone conversations and signaling encryption protects against tampering with telephone signaling packets,” Cisco said in a statement.