Convergin is offering carrier software that could help speed mixed cellular/Wi-Fi phone services that can save businesses money and support multimedia services.

Called Accolade, the software runs on a server in carrier networks and translates signals between legacy wireless networks and networks supported by Session Initiation Protocol (SIP ), which tells networks where customers can be reached. This enables carriers to deliver calls to customers based on where they are rather than by simply calling a number.

For example, the software would support a service that calls customers' wireless phones over cellular networks when they are driving, but call the phones over a corporate Wi-Fi network when customers are at work. This requires a dual-mode cellular/Wi-Fi phone.

The advantage of this is that using the Wi-Fi network is less expensive than paying for cellular minutes, and the use of SIP allows companies to add other communications methods such as instant messaging and e-mail, says Joe McGarvey, an analyst with Current Analysis.

Accolade could let service providers migrate their networks gradually to SIP, while keeping their legacy infrastructure in place.

The software also can support signaling in an all-SIP network under the standard network architecture known as IP multimedia subsystem (IMS). This standard defines the network elements needed to support SIP services, and Convergin says its Accolade platform meets the IMS definition of a service capability interaction manager. It can pull together sets of other network elements on the fly to provide defined services.

Because service providers can use Accolade to blend SIP and legacy networks, they can cap their spending on legacy network gear and start phasing in SIP-based equipment, McGarvey says. It also enables carriers that offer only cellular service to keep their cellular infrastructure in place and add on support for VoIP over Wi-Fi services, he says. This could help carriers such as cable operators to integrate wired phone services with mobile phone services via partnerships with wireless carriers that own mobile spectrum and become mobile virtual network operators, Convergin says.

The company says its software could encourage service providers to offer IP-based services. For instance, a carrier could invest in an IP Centrex platform and use it to support Centrex service that extends to IP phones, cellular phones and traditional wired phones.