Why Are My Calls Failing? Every Reason & Fix (2026)
Complete troubleshooting guide for failed calls. Covers cell phone signal issues, VoIP packet loss, STIR/SHAKEN blocking, international dialing errors, SIP error codes, carrier outages, and rural call completion problems.
Calls fail for five main reasons: no signal, wrong number format, carrier blocking (including STIR/SHAKEN spam filters), network congestion, or insufficient balance. The fix depends on the cause — and most failed calls can be resolved in under a minute.
This guide covers every reason your calls might fail — from cell phone signal issues to VoIP packet loss, international dialing mistakes, STIR/SHAKEN blocking, carrier outages, and rural call completion problems. Each section includes the specific fix.
Quick Diagnostic: Why Did Your Call Fail?
1. Fails immediately (no ring): No signal, airplane mode, invalid number, blocked by carrier, or unpaid balance.
2. Rings once then fails: Recipient blocked your number, or call forwarding to a disconnected line.
3. Drops mid-conversation: Weak signal, handoff between towers, network congestion, or VoIP packet loss.
4. Goes straight to voicemail: Recipient's phone is off, in Do Not Disturb, no signal, or they blocked you.
5. Choppy/robotic audio then drops: VoIP jitter (>30ms), packet loss, or codec mismatch. Switch to wired connection.
Cell Phone Call Failures
| Problem | Cause | Fix |
|---|---|---|
| No signal (0 bars) | Out of coverage or carrier outage | Move to window/higher floor. Toggle airplane mode. Try WiFi calling. |
| Call drops mid-call | Tower handoff failure, weak signal | Stay in one location. Avoid elevators/tunnels during calls. |
| "Number not in service" | Disconnected or invalid number | Verify the number. Check for missing area code (10-digit dialing required). |
| "All circuits are busy" | Network congestion | Wait and retry. Use VoIP as alternative route. |
| One-way audio | NAT traversal or firewall issue | Restart phone. Switch between WiFi and cellular. |
2025 data: J.D. Power found 8 problems per 100 connections, down from 11 PP100 in 2024 — the lowest since 2018.
Why International Calls Fail
Wrong Format (Most Common): Always use E.164: +[country code][number without trunk prefix]. Wrong: +44 020 7946 0958 (extra 0). Correct: +44 20 7946 0958.
STIR/SHAKEN Blocking: As of December 2025, 86% of large carrier calls carry STIR/SHAKEN authentication. International and VoIP calls often get lower attestation levels, causing them to be flagged or blocked.
Country-Specific VoIP Blocks: UAE, Oman, parts of China, and North Korea block or restrict VoIP calls.
Carrier Restrictions: Many US carriers require international calling to be enabled on your account.
VoIP Call Failures (Technical)
| Issue | Threshold | Symptoms | Fix |
|---|---|---|---|
| Packet Loss | >1% = noticeable | Choppy audio, missing words | Use wired connection, close apps |
| Jitter | >30ms = audible | Robotic voice, garbled audio | Enable QoS on router, use ethernet |
| Latency | >150ms = delay | Echo, talking over each other | Reduce network hops |
| NAT Traversal | Symmetric NAT | One-way audio, call drops | Enable TURN relay |
| Codec Mismatch | G.729 tandem | MOS drops 3.92 to 2.68 | Use G.711 or Opus |
Quality benchmark: MOS 1-5 scale. IT teams use 3.5 as minimum acceptable. Below 3.5 = robotic distortion. Above 4.0 = professional quality.
Common SIP Error Codes
| Code | Name | Meaning |
|---|---|---|
| 403 | Forbidden | Auth failure, IP blocked, or negative balance |
| 404 | Not Found | Number not in service |
| 408 | Timeout | No response in 32 seconds |
| 480 | Temporarily Unavailable | Recipient offline or not registered |
| 486 | Busy Here | Recipient on another call |
| 487 | Request Terminated | Call cancelled |
| 503 | Service Unavailable | Server overloaded |
| 603 | Decline | Recipient rejected the call |
Diagnostic rule: A 4xx/5xx error rate above 5% indicates a systemic problem.
Major Carrier Outages (2025-2026)
Global network outages increased 33% from Jan-May 2025. US accounted for up to 55% of all global outages.
January 2026 Verizon outage: 178,000+ reports on Downdetector. Even disrupted 911 calls in Washington DC area.
45% of all outages in 2025 were caused by power issues.
Rural Call Completion Problems
The FCC found rural call answer rates are approximately 2% lower than non-rural areas — and it hasn't improved. Intermediate carriers drop calls to rural areas because termination costs more. The FCC collected over $6 million in fines from carriers for failures.
Step-by-Step Troubleshooting
1. Check signal: Move to a window, toggle airplane mode on/off.
2. Verify number format: US: 10 digits. International: +[country code][number without leading 0].
3. Check for carrier outages: Visit Downdetector or carrier status page.
4. Check account: Verify balance (prepaid) or no overdue bills. Check international calling enabled.
5. Restart phone: Clears cached connections, re-registers with towers.
6. Try alternative: Use VoIP (BubblyPhone, Google Voice) to bypass carrier network issues.
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