SIPStation terminating calls at exactly 15 minutes after successful session refresh

Sangoma Trunking
1

We are experiencing repeatable outbound call disconnections at almost exactly 15 minutes when calling a conference service through SIPStation.

This was initially reported on July 21, 2026. SIPStation support advised that it was likely connected to a temporary latency incident and stated that the issue had been resolved. However, we reproduced the same failure again on July 24 with full Asterisk SIP logging and a packet capture running.

The captured sequence is very clear:

  • The call connected successfully at approximately 8:00:50 AM Central.
  • The session negotiated Session-Expires: 1800;refresher=uac.
  • At exactly 900 seconds, FreePBX correctly sent a session-refresh UPDATE.
  • SIPStation responded approximately 17 milliseconds later with SIP/2.0 200 OK.
  • Approximately 1.43 seconds after accepting the successful refresh, SIPStation sent a BYE to FreePBX.
  • The BYE contained Reason: Q.850;cause=16;text="NORMAL_CLEARING".
  • FreePBX disconnected the internal extension only after receiving the BYE.
  • The other participants remained connected to the conference, confirming that the conference itself did not end.

The SIPStation-facing Call-ID is:

f21051b9-d490-4832-8d98-e6d9183d8f3b

The BYE arrived from SIPStation signaling address 192.159.66.3 with User-Agent: SIPStation 2.11.3.

This is not an unanswered refresh, an RTP timeout on our PBX, or the internal extension hanging up. FreePBX performed the required refresh, SIPStation accepted it, and SIPStation then terminated the call immediately afterward.

We have asked SIPStation to trace the call through its upstream carrier and determine:

  • Which upstream component originated the termination
  • Why the call was cleared immediately after the successful 900-second UPDATE
  • Whether the UPDATE was properly forwarded through the complete carrier path
  • Whether an upstream BYE or other carrier response caused SIPStation to clear our leg
  • Whether this results from a standard SIPStation configuration or carrier limitation

Unfortunately, obtaining support has also been difficult. I called twice today to request escalation. The first support call was disconnected while waiting, and the second remained on hold for approximately 20 minutes without reaching anyone.

This is disrupting active business conference calls and requires urgent escalation. Has anyone else experienced SIPStation calls terminating at exactly 15 minutes following a successful session refresh?

We have retained the complete PCAP and SIP logs and can provide them directly to Sangoma or SIPStation support. If this is a known configuration or interoperability issue, we need the applicable correction. If it is an inherent carrier limitation, we need confirmation so we can begin evaluating another SIP carrier.