With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cagwNetworkBehindMs
Cisco's ASN Gateway Network Behind Ms
1.3.6.1.4.1.9.9.638.1.2.1.1.10
The number of mobile stations that may have a network behind them.
Back to CISCO-ASN-GATEWAY-MIB MIB page.
IPHost Network monitor allows you to monitor cagwNetworkBehindMs on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco multiplexers right now.