Skip to content

DID Rings but Call Drops

Symptom: inbound call to a DID rings (caller hears ringback), but the call drops before or shortly after answer. No voicemail catches it. CDR shows it as NO ANSWER or FAILED.

Different from "call disconnects immediately" — that's an answer-then-drop within 1-2 seconds. This drops at or before answer.

Most Likely Causes

  1. Inbound route destination is broken — points at a deleted IVR, queue, or extension.
  2. Time Condition non-match destination is "Hangup" — call falls into the void after hours.
  3. Extension destination has no devices registered.
  4. Ring group times out and falls to a destination that doesn't exist.
  5. DID format mismatch — call falls through to catch-all → catch-all goes to "Hangup."
  6. Carrier sending bad SIP — call setup never completes from their side.

Diagnose

# Find the inbound call in CDR:
mysql -u root cdr -e "SELECT calldate,src,dst,dstchannel,disposition,lastapp,lastdata
                     FROM cdr ORDER BY calldate DESC LIMIT 10;"
# lastapp + lastdata tell you where the call was when it ended.

# Live trace:
asterisk -rvvvvv
# Have the test call placed. Trace will show:
#  - Which inbound route matched
#  - The destination it set
#  - Each module entered (Goto, Macro, Dial, etc.)
#  - The disposition at hangup

Fix

Match the trace output:

  • Route matched but went to "Hangup": open the inbound route → Set Destination → pick a valid endpoint.
  • Time Condition went non-match: check Time Group hours, system clock, or set a sensible non-match destination (announcement → voicemail).
  • Extension destination but no devices: the user's phone is unregistered. See Phone Won't Register.
  • DID format mismatch: the DID arriving doesn't match any inbound route DID Number. Update the route to match the actual format from sngrep capture.
  • Catch-all fix: add a catch-all inbound route with blank DID matching anything → destination = a "we got your call" announcement → voicemail.

When to Escalate

CDR shows the call never reached UnifiedBX dialplan (no from-trunk entry) — this is on the carrier side. Open a ticket with them.