Call Forward All / No Answer / Follow Me (no confirm) connect but no audio

[apv04]

FusionPBX 5.5 - Call Forward All / No Answer / Follow Me (no confirm) connect but no audio​

Hi everyone,

I'm troubleshooting an interesting issue and would appreciate any ideas.

Environment​

• FusionPBX 5.5 (freshly upgraded from 5.2)
• FreeSWITCH 1.10.11
• Debian 12
• IP authenticated SIP trunk to Sýn (Vodafone Iceland) using a Cirpack SBC
• No NAT between FusionPBX and the carrier

Problem​

Calls connect successfully, but there is no audio in either direction when using:

• Call Forward All
• Call Forward No Answer
• Follow Me (Confirmation disabled)

The SIP signaling completes successfully and the call remains connected until one side hangs up.

What works​

• Incoming calls have two-way audio.
• Outgoing calls have two-way audio.
• Internal extension calls have two-way audio.
• Ring groups work.
• Follow Me with "Confirm Call" enabled works perfectly.
• If I assign the DID to an extension, set the ring timeout to 0 seconds, and then forward the call, it also works perfectly.

The only scenarios that fail are the ones that perform an immediate forward.

What I've already checked​

• Upgraded FusionPBX from 5.2 to 5.5.
• Database Schema, App Defaults, Menu Defaults and Permission Defaults completed successfully.
• Media Mode tested with:
  • Normal
  • Bypass Media
  • Proxy Media
    (No difference.)
• RTP/SIP addresses are correct.
• Codec negotiation is PCMA on both legs.
• Calls are bridged successfully.
• SIP signaling appears normal.

<span>show channels</span> during the failing call shows:

• Inbound leg reaches <span>CS_EXECUTE</span> with <span>bridge</span>.
• Outbound leg reaches <span>CS_EXCHANGE_MEDIA</span>.
• Both legs negotiate PCMA.
• The bridge stays up normally.

Observation​

The most interesting part is this:

• Immediate forwarding → Connected, no audio.
• 0-second extension timeout, then forward → Audio works.
• Follow Me with "Press 1 to accept" → Audio works.

This makes me think there is a difference in the media establishment or bridge path used by immediate forwarding versus forwarding after the call has first been presented to an extension or IVR.

Has anyone seen this before with FusionPBX/FreeSWITCH, particularly when using an IP-authenticated SIP trunk or Cirpack SBC?

Any ideas on what to investigate next would be greatly appreciated.