Endpoint identifier (EPID): A unique identifier of a Session Initiation Protocol (SIP) endpoint. 

When enabled (1), it adds an 'epid' tag to the 'From'header.

Example: From: <sip:1014@192.168.178.210>;tag=dd6d1a91-800f-4037-ac55-322665c29b7b;epid=9e74a599

Provisioning ParameterValue
SipProvider.<id>.InstanceCoding 

1 = Adds an 'epid' tag to the 'From'header

2 = add '+sip.instance' to 'Contact' header