In an example embodiment, a solution that allows a PBX to utilize bridged mobile or desktop applications for collaboration and softphone use is provided. The solution works in conjunction with existing hardwired PBX devices without requiring additional hardware such as an edge router to be integrated with the PBX hardware. Incoming calls are able to ring a user's hardwired device, such as a desk phone at an office, while simultaneously ring mobile device or desktop applications (apps). App users can place outbound PSTN calls and dial PBX extensions just as if they were using their hardwired device. Additionally, PSTN services are utilized from the existing PBX rather than bypassing the existing PBX, which makes tracking and billing more straightforward. A Session Initiation Protocol (SIP) tie trunk is used between the existing PBX and a software bridge controller.