SIP Vicious Call

[BGH]

In our organization, we keep receiving random calls from: 60200, 501
When we answer the call, the call drops.

It looks like SIP Vicious call or ghost call.

We have cisco ASA  Firewall

I have very new in Cisco Firewall.

The VLAN for VOIP is 650.

Can someone guide or advise me, what shall i check in our Cisco Firewall step by step.

I do have access to Cisco Firewall through Cisco ASDM.

[Andrew Skelly]

What are you expecting to find in your firewall?  If the calls are coming in from an external source I would engage your carrier with call examples to determine if they are spam/robocalls or if they are legit calls.