Detailed technical records, CDR statistics, quality-metric analysis, and support logs regarding Ticket #387285. This page carries the full evidentiary detail behind the executive summary.
On the night of June 29, 2026 at 23:29 ICT, OpenFax forwarded Telnyx's own “Voice services update – all regions” maintenance notice back to Telnyx support and asked directly: “Is incident update related?”
“I've checked the Telnyx Status Page and found no published incident specifically named 'Voice services update - all regions.'” Telnyx support — June 29, 23:31 ICT
“I don't see a specific 'Voice services update – all regions' incident currently posted on the public status page.” Telnyx support — June 30, 23:33 ICT
Both replies listed only unrelated wireless/roaming incidents as active. This is the same maintenance window that appears in the public status-page anchors on the executive timeline (June 29 entry). OpenFax identified the correct cause within roughly an hour of the notice going out — and was told by Telnyx's own support that it did not exist.
MOS (Mean Opinion Score) is a direct, objective measure of whether audio was actually flowing. Average MOS sat rock-steady at 4.44–4.49 every single month from August 2025 through June 26, 2026 — no drift, no gradual decline. Then, hour by hour:
| Time (UTC) | Avg MOS | Interpretation |
|---|---|---|
| Through Jun 26 | 4.44–4.49 | Normal — eleven months of flat baseline |
| Jun 29, 11:00 onward | ~1.0–1.5 | Audio effectively unusable — earliest bad reading in the data |
| All of Jun 30 | ~1.0–1.5 | Still broken |
| Jul 1, 04:00–05:00 | 1.000 | Still broken (only 4 calls logged) |
| Jul 1, 13:00 onward | 4.44–4.49 | Snaps back to baseline instantly — exactly at the AWS/regional cutover |
The abandoned-call rate stayed elevated (30–35%) for roughly four more hours after MOS recovered, only normalizing by July 2 — consistent with backlog/retry traffic clearing, not a new fault.
How OpenFax isolated the failure, step by step, on its own.
100.79.0.23 as the VXC NAT address that Telnyx's re-INVITE was being sent to.Key facts established across the support engagement.
SJC-SV-10-200-708-205-2219-B & SJC-SV-1-200-708-205-2219-A (VLAN 314).Monthly abandoned-call rate against the 20% surcharge threshold, August 2025 through the July 1–6 outage window. Notably, the rate was already at 16.09% in September 2025 — a month before the October 28 policy announcement — i.e., the pattern predates the policy rather than resulting from it.
The 20% billing threshold was exceeded in Nov '25 (23.85%) and Jun '26 (20.17%). The July 1–6 window averaged 22.64%, driven almost entirely by July 1's record daily spike of 32.53% during the outage.
Invoice-billed surcharge units, cross-validated against an independent recompute from raw CDRs.
| Month | Invoice-billed abandoned calls | Independent CDR recompute | Variance | Amount billed | Rate |
|---|---|---|---|---|---|
| Nov 2025 | 512,752 | 512,750 | 2 calls (≤0.01%) | $2,563.76 | 23.85% — over threshold |
| Jun 2026 | 339,966 | 339,936 | 30 calls (≤0.01%) | $1,699.83 | 20.17% — over threshold |
| Jul 1, 2026 | (during outage window) | — | — | 32.53% daily peak | |
The invoice figures and the CDR-derived figures (Hangup Details = recv_cancel) are independently sourced and agree to within 0.01%. This cross-validates the CDR analysis against what Telnyx actually billed: the fee calculation is not in dispute — the question is whether outage- and configuration-driven abandonment should be exempt from it.
Telnyx issued the abandoned-call surcharge notice on October 28, 2025, effective November 1, 2025: $0.005 per abandoned call, applied only when the monthly abandoned rate exceeds 20%. Telnyx's own confirmed definitions: a Short Duration Call is under 6 seconds; an abandoned call is one where the originating side disconnects during ringing/setup, before answer.