Have an existing FS app using 800 inbound with SIP carrier. No IP address is sent.

Below is example of good call with proper ANI and DNIS sent from our carrier. (Modified to protect info.)

12:27:43 lsvc:Inbound call from ANI xxxxxxxxxx to DNIS 800xxxxxxx
12:27:44 (121094) lsvc:SERVER_TYPE is: 0
12:27:44 (121093) lsvc:Staff 2 logged in
12:27:47 (121094) lsvc:Caller is entering his phone number
12:27:48 (121093) lsvc:disconnected reason was NONE
12:27:48 (121093) lsvc:lsvc_in: completed call successfully
12:27:52 (121094) lsvc:The caller typed in a home phone number of xxxxxxxxxx

Below is example of hits we are taking that are not being sent from our carrier (I assume direct hits to router)

10:00:12 lsvc:Inbound call from ANI 100 to DNIS 001448703928456
10:00:13 (121218) lsvc:SERVER_TYPE is: 0
10:00:45 (121218) lsvc:disconnected reason was NONE
10:00:45 (121218) lsvc:Caller is entering his phone number

My question is there a way for me to prevent the fake ANI's from connecting?