Budget Failover Solution for Remote Offices for Microsoft UC

When building a telephone infrastructure based on Microsoft Lync / Skype For Business, quite often the question arises of how to organize telephony fault tolerance at a remote office in the event of a WAN channel falling to the central office. In most cases, the SBA solution is used, which is a joint solution of Microsoft and partners. AudioCodes has three SBA options, based on the Mediant 800/1000/2600. This solution uses a voice gateway with a built-in Intel based server, where Microsoft Windows is installed with Lync failover components. Due to the additional server and the Windows license, the solution is not the most budget-friendly and, as a rule, is designed for an office of 50 or more employees. And what to do if you want to implement the resiliency of telephony based on Lync / Skype For Business for a small office.

AudioCodes for such purposes has developed a special technology based on its own phones and voice gateways / SBC - OVR (One Voice Resiliency). When using this technology, on an IP phone compatible with Microsoft Lync / Skype For Business, its main SIP Registrar is not the Front End server (which is configured by default when connected to Microsoft Lync), but the Mediant address. Next, Mediant registers this phone with Microsoft S4B. That is, during normal operation, the IP phone is connected to Lync / S4B through Mediant, while the functionality of the IP phone remains full and all calls are controlled by Microsoft Lync / S4B. At the time of the fall of the channel to the central office, Mediant, having all the information about subscribers, begins to make calls between subscribers and provide calls to the city. Connection diagram is presented below:


In this case it is important to note the following points:

1. With a regular connection, the IP phone is connected via SBC in order to ensure the minimum time for the system to switch to emergency mode and back. According to the operation algorithm, Lync / S4B, the IP phone must check the connection every 15 minutes and to avoid a timeout of 15 minutes, the Mediant itself constantly checks the connection with MS Lync and switches to the backup mode almost instantly. Return to normal mode also happens instantly.
2. This functionality works with the entire line of AudioCodes IP phones compatible with Microsoft Lync / S4B.
3. This functionality is supported on the following AudioCodes voice gateways - Mediant 800/1000/2600 and higher.
4. This option of fault tolerance is provided regardless of how the remote office works. The system can work as if it is connected to the Front End server through a VPN, or in the case of a remote office working through the Edge server.