I think this OID is what you are looking for
Name: ccmIndex
Type: OBJECT-TYPE
OID: 1.3.6.1.4.1.9.9.156.1.1.2.1.1
Full path: iso(1).org(3).dod(6).internet(1).private(4).enterprises(1).cisco(9).ciscoMgmt(9).ciscoCcmMIB(156).ciscoCcmMIBObjects(1).ccmGeneralInfo(1).ccmTable(2).ccmEntry(1).ccmIndex(1)
Module: CISCO-CCM-MIB
Parent: ccmEntry
Next sibling: ccmName
Numerical syntax: Gauge (32 bit)
Base syntax: Unsigned32
Composed syntax: CcmIndex
Status: current
Max access: not-accessible
Description: An arbitrary integer, selected by the local CCM,
which uniquely identifies a CallManager in a call manager
cluster.