I'm very interested to hear what others have done to filter out and reject incoming SPAM calls. For us, this is a very tricky thing to do considering most of these calls have spoofed numbers & Caller ID info. Simply rejecting certain numbers either at the H323 GW, or CUCM does nothing as they can instantly change the calling number. Rejecting unknown callers is also not an option, as Caller ID is often spoofed or left blank with legitimate callers. I am currently looking into a way to possibly reject multiple call attempts from/to the same number, but not sure if this is possible. Has anyone else had any success in preventing these SPAM calls from reaching their users? Our setup is PRI --> H323 GW --> CUCM --> End User Extension.
This is virtually impossible to battle, because like you say they morph the caller ID.
If this is hindering your operations, you might want to consider putting an IVR in the path that requires manual input. and also involve your telco to see to what extend they can put blocks in place and or black list
We're battling this issue as well. Just imported a bunch of DIDs for staff and they started getting a bunch of spam calls. Blocking the numbers is not an option since they will easily change the calling no. I do like the suggestion of some sort of IVR. I'm thinking maybe Unity Connnection could come in handy. Maybe we can ask the caller to press 1 to be connected or something along those lines.