AOL this week is testing a new integrated communications version of its AOL Instant Messenger service, which incorporates SMS into VoIP functionality into its mobile and PC clients.

Called Triton, AOL has been Beta testing the service since April and plans to release a “Preview” version of the software to the general public this week. Powering the service is Plaxo’s unified phone book software, creating a centralized address book from which a customer can send an instant message, an e-mail or an SMS message as well as initiate a VoIP call over AOL’s new peer-to-peer TotalTalk service.

For the wireless industry, the SMS feature means far greater penetration into the mobile network. While AOL has launched IM services over numerous carriers’ networks over Oz’s and Comverse’s mobile messaging platforms, there are far fewer IM enable devices in the market today than SMS devices. The service would allow an AIM user on a PC to send an SMS to the vast majority of mobile users.

“We rebuilt the AIM service from the ground up to make it a powerful communications tool that offers unprecedented versatility,” vice president and general manager of AIM Chamath Palihapitiya said in a statement. “Our goal is to let people focus on who they want to talk to and what they want to say, instead of worrying about which software application they need to open.”