With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cmedxGatewayMaxContexts
cmedx Gateway Max Contexts
1.3.6.1.4.1.9.10.104.1.1.1.1.4
Maximum number of contexts is allowed in this media gateway link.
Back to CISCO-MEGACO-EXT-MIB MIB page.
IPHost Network monitor allows you to monitor cmedxGatewayMaxContexts on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco routers right now.