From the latest UC Software 5.9.2 Admin Guide >here< the factory default for this parameter is 1.
We cannot confirm this without having a backup attached as other settings may affect this. The next step would be a support ticket.
In order to raise a support ticket, you need to work with your Poly reseller as they may need to do this for you.
End Customers are usually unable to open a ticket directly with Poly support. Available End User Poly services offerings are detailed here
If this is some sort of an Internet discounter providing your MAC address or your Poly devices serial will enable us to look up who would be able to support you. This may not be who you purchased the Poly device from.
Please ensure to provide some feedback if this reply has helped you so other users can profit from your experience.
Notice: This community forum is not an official Poly support resource, thus responses from Poly employees, partners, and customers alike are best-effort in attempts to share learned knowledge. If you need immediate and/or official assistance please open a service ticket through your proper support channels. Please also ensure you always check the VoIP , Video Endpoint , Skype for Business , PSTN or RPM FAQ's