How to block different calls

[stanzin]

One of our dept (of 4 users) has been reporting of spam calls happening everyday. They get 7-12 calls a day from different numbers and often masking as someone from the same building? Apart from changing their number which would be the last resort what would be a viable solution?

Call flow:

Phone> Callmanager( SIP trunk) > SIP MGW > Vendor

Any suggestions would be greatly appreciated.

[Kathy N.]

This might help.  We do this to block calls in our CUBE:

Block Incoming Calls based off of ANI on router

The following is an example of how to setup call blocking based off of incoming Caller's ANI. 

Note: create voice translation-rule to use for blocking numbers.  Don't use an existing rule unless you know it was created for this purpose.

router#show voice translation-rule xx

Check for an unused rule # to assign

Add rule for that phone number - Example using rule 3:

router#conf t

router(config)#voice translation-rule xx

router(cfg-translation-rule)rule 3 reject /1112223333/

To remove; do above but at last step enter:

router(cfg-translation-rule)no rule 3 reject /1112223333/

[stanzin]

Thanks Kathy, this would have been nice if it’s just couple of numbers. In my case, (user - group of 4) are getting calls from different numbers and often masked as internal numbers. So, is getting a little tough to stop. 

thanks 

[Roger Kallberg]

This document might get you on your way with this. Blocking Calls Based on Calling Party ID 

[stanzin]

Thanks for the great document.

Quick question, by doing so will it not block all non DN ? Will they still be able to receive calls outside of the company's #s?

[Roger Kallberg]

Only numbers that are defined as blocked, by specifically matching a block translation pattern, will be blocked. Anything else will match a wild card translation pattern that allows the call to route.

In general it would be impossible to receive a call from an external caller that present as an internal calling number, so for this my recommendation would be to create block translation pattern(s) that matches your entire internal number series as these are most definitely suspect.

[stanzin]

The thing is, the spam calls comes with different area code and never the same number. And, like i mentioned earlier they sometimes mask the call as its coming from the same company. So, its not very easy for me to put a block

[Roger Kallberg]

Let me ask you a question. How do you think that you’ll be able to block the call(s) if you do not configure what to specifically not allow?

As @Kathy N. wrote scammers do constantly source the origin of the calls from different numbers, that are often spoofed, so it’s not even coming from a number that they own. This makes it quite hard, if not impossible, to block these calls without also affecting legit calls that truly originates from the same calling number as the scammers use.

[stanzin]

Sorry! I don't know, that's why I put the question out.

Because it's different numbers, different area code and never the same number I didn't know how i could put a block. But I posted the question just in case if anyone faced the same problem and what solution they went for.

[Kathy N.]

@stanzin, unfortunately spammers know that it's almost impossible to block numbers when they constantly change the Caller ID since there could be valid numbers in the range that has the wild card characters.  I don't know of any resolution to this so many of our staff will let calls go to voice mail if they don't recognize the number and then call back if a voice mail message is left.  If you have a call center, this probably isn't an option though.

[stanzin]

Exactly! that's why I didn't wanted to block an area code and stop valid calls getting through.

Yea, I guess I will speak to the user and if they are OK, change their number or have them deal with it

Thanks