AiPBX

Inbound Caller ID Blacklist & Spam Blocker

AiPBX provides high-performance inbound spam filtering and caller number blocking designed to intercept nuisance callers, robocalls, and fraud attempts at trunk entry before they tie up extensions, queues, or IVR channels.

Architecture & Sub-Microsecond AstDB Lookup

When an incoming call arrives on any configured trunk ([from-trunk-<name>]), it immediately passes through the [sub-inbound-blacklist] dialplan subroutine:

1. Exact Number Match via AstDB:
   • Active blocked numbers are stored in Asterisk’s in-memory key-value database (AstDB) under blacklist/<number> and blacklist_action/<number>.
   • Lookups execute with zero SQL overhead and complete in sub-microseconds without database queries.
2. Wildcard & Dialplan Pattern Matching:
   • Prefix blocks (e.g., _0850., _+1800.) are dynamically compiled into the [sub-inbound-blacklist-patterns] context.
   • Asterisk pattern matching is evaluated when an exact match is not found.
3. Early Rejection Before Queue/IVR Execution:
   • Rejected calls never consume trunk channel limits, never trigger IVR speech synthesis, and never ring internal extensions.
   • The CDR record is tagged with CDR(accountcode) = SPAM_BLOCKED and CDR(userfield) = Blacklist: <action>.

Block Actions

Administrators can choose how blacklisted calls are handled:

Action	Technical Mechanism	Description
Busy (busy)	Playtones(busy) & Hangup(17)	Returns ISDN 17 / SIP 486 Busy Here. The carrier informs the caller that the line is busy.
Congestion (congestion)	Playtones(congestion) & Hangup(34)	Returns ISDN 34 / SIP 503 Service Unavailable / Circuit Busy. Simulates a network failure.
Drop (drop)	Hangup(16)	Terminates the call immediately with normal clearing (ISDN 16) without playing audio or answer supervision.
Announcement (announcement)	Answer() + Playback(ss-noservice) + Hangup(1)	Answers the call and plays the standard telecom “number is not in service” announcement before disconnecting.

Quick Blocking from Extension CDR

The web interface (/blacklist) includes a quick lookup tool:

• Enter an extension number (e.g. 101) to automatically fetch the last inbound caller ID from call logs and populate the blocking form in one click.

CSV Bulk Import

Numbers can be bulk-imported using CSV files (.csv):

number,title,action
08501234567,Telemarketing Spam,busy
08507654321,Robocall,congestion
_0850.,Entire 0850 Prefix Block,drop

If the action column is omitted, the user-selected default action is applied.

CLI & Direct AstDB Management

Blacklist records can also be viewed or managed directly via the Asterisk CLI:

# View active blacklisted numbers
asterisk -rx "database show blacklist"

# Add a number manually
asterisk -rx "database put blacklist 08501234567 1"
asterisk -rx "database put blacklist_action 08501234567 busy"

# Delete a number manually
asterisk -rx "database del blacklist 08501234567"
asterisk -rx "database del blacklist_action 08501234567"

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