OpenScape Voice OpenScape Voice creates technology choices that enable customers to implement communication strategies that are right for their businesses. OpenScape Voice is a 100% software VoIP switchboard solution from Siemens that supports SIP protocol, running on the SUSE Linux Enterprise platform. With the ability to support up to 100,000 subscribers on a single system, the ability to manage 3000 branches and the OpenExchange feature allows OpenScape Voice to be compatible with all systems or terminals that support the SIP protocol.