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FreePBX / Asterisk integration

Reference setup for FreePBX 17 / Asterisk 22. Adapt extension numbers and hostnames for your deployment.

Overview

Piece Purpose
PJSIP trunk sip-dmr-exchange → portal host UDP 5060
Custom dialplan IVR contexts [dmr-portal], [sip-dmr-ivr], [sip-dmr-headers]
Custom Destination Registers IVR entry for FreePBX GUI
Misc Applications Per-extension allowlist for feature code

Extension Routes do not gate internal feature codes

FreePBX Extension Routes only control outbound routes. To restrict who may dial your portal feature code, use Misc Applications (or equivalent dialplan ACL).

1. Custom Destination (required for GUI)

Before Misc Applications destinations work in the FreePBX GUI, register the dialplan target:

Admin → Custom Destinations → Add

Field Value
Description DMR Portal IVR
Custom Destination dmr-portal,234,1
Return off

Submit → Apply Config.

Without this step, Misc Applications show Bad Dest: dmr-portal,234,1 in the destination dropdown.

2. PJSIP trunk

Configure custom PJSIP files (or GUI trunk equivalent):

File Purpose
pjsip.endpoint_custom.conf Endpoint sip-dmr-exchange
pjsip.aor_custom.conf AOR to portal host
pjsip.identify_custom.conf Identify by portal IP
  • IP authentication, no registration
  • Portal host: your-portal.example.com:5060

3. Dialplan contexts

Add to extensions_custom.conf (feature code 234 shown as example):

[dmr-portal]

  1. Answer, set callsign variable from AMPUSER cidname
  2. Play welcome prompt
  3. Goto(sip-dmr-ivr,start,1)

[sip-dmr-ivr]

  1. Read() talkgroup (digits only, validate pattern)
  2. Play connecting prompts
  3. Dial(PJSIP/${DMRTG}@sip-dmr-exchange,180,b(sip-dmr-headers^addheaders^1))
  4. On congestion / unavailable → play portal-busy (exchange at capacity)
  5. Max retries → goodbye

[sip-dmr-headers]

Pre-dial subroutine:

  • X-Auth-Token — from secure file on PBX, matches exchange SIP_AUTH_TOKEN
  • X-Callsign — uppercase cidname
  • X-DMR-SSID — optional (e.g. 99 for SystemX suffix)

4. Access control (Misc Applications)

Each user who may dial the portal needs one Misc Application:

  1. Applications → Misc Applications → Add
  2. Description: DMR Portal (CALLSIGN)
  3. Feature Code: 234/_EXTNUM — e.g. 234/_10018 for extension 10018
  4. Destination: Custom Destinations → DMR Portal IVR
  5. Submit → Apply Config

Denied users hear “cannot complete as dialed” — no IVR, no trunk.

Remove access

Delete or disable the user's Misc Application row → Apply Config.

5. IVR sounds

Install under /var/lib/asterisk/sounds/custom/sip-dmr/:

File Use
welcome Start
enter-tg Talkgroup prompt
invalid Bad input
connecting, systemx Before dial
portal-busy Exchange returned 503
goodbye Too many attempts

Verify

asterisk -rx "dialplan show customdests"
asterisk -rx "dialplan show 234@dmr-portal"
asterisk -rx "dialplan show 234/_10018@app-miscapps"   # example allowlisted ext
asterisk -rx "core show channels concise" | grep -E "234|sip-dmr|dmr-portal"
mysql asterisk -e "SELECT miscapps_id, description, ext, dest FROM miscapps;"

What not to do

  • Do not add a global exten => 234 in [from-internal-custom] — bypasses allowlist
  • Do not create PJSIP extension 234 — it is dialplan-only
  • Do not commit auth tokens to git

Portal busy (capacity)

When MAX_ACTIVE_CALLS is reached, exchange returns SIP 503. Route DIALSTATUS of CONGESTION / CHANUNAVAIL to a portal-busy prompt.

Multi-portal failover (advanced)

When running multiple portal nodes:

  1. Add second trunk e.g. sip-dmr-exchange-b
  2. Sequential Dial() in IVR to try primary then secondary
  3. Set per-node MAX_ACTIVE_CALLS

Misc Application allowlist unchanged.

Last update: August 17, 2026 21:08:54
Last updated by: MØVUB
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