How to block calls

Unwanted calls can be blocked depending on various parameters: CallerID, destination number, IP, etc.

Block calls with a specific CallerID

Instructions on how to block calls, which have a specific CallerID can be found here.

Block calls with a specific Destination

Instructions on how to block calls to some specific destinations can be found here. Destinations can be blocked for a specific User, as well as for all Users.

Block calls with short destination/CallerID numbers

It is possible to block a call which has a destination number with a specific number of digits. This way calls to short numbers can be blocked.
Instructions on how to block short destination numbers can be found here.
The same can be done with short CallerIDs: CallerID localization rules need to be used instead of Destination localization rules.

Block all calls from a specific IP

Fail2ban blocks all IPs which try to make to many unauthorized calls. However, sometimes there is a need to block all traffic, which is coming from a specific IP, manually. This can be done using iptables.
Instructions on how to manage iptables and block/unblock IPs can be found here.

Block a large amount of specific destination numbers

It is possible to block a list of specific destination numbers. MNP add-on is used to do this.
MNP add-on allows to upload specific numbers with a prefix to the database. If a call comes with the destination number, which is in the MNP database, a prefix will be added to the destination number. Then a call can be blocked using Localization rules. For example, you upload such numbers and prefixes:

number,      prefix
37067012346; 112233
37067012347; 112233
37067012348; 112233 

Then you create a Localization rule:

Cut: 112233, Add: , Change LCR to This LCR: Empty LCR

Now once the call comes to 37067012346, a prefix will be added (11223337067012346). Localization rule will be applied and this call will be routed to an empty LCR. Therefore such call will fail.

Blocking calls by using Blacklist functionality

Blacklist functionality is based on a smart logic which puts a 'score' on the call by its SRC, DST or SIP signaling IP and allows blocking calls with a high score. For example, you can block a destination/CallerID number, if it made X calls during Y seconds.
More information can be found here.