Skip to main content
Use this guide to diagnose and fix common voice call issues. Start with the symptom you’re experiencing.

​
Quick Diagnosis

Check in order:
  1. Verify credits balance in Console → Billing
  2. Check geo permissions for destination country
  3. Verify caller ID is a Plivo number or verified
  4. Review hangup cause in call logs
Common causes:
Hangup CauseSolution
destination_country_barredEnable country in Console → Voice → Geo Permissions
unknown_caller_idUse Plivo-rented number as caller ID
insufficient_creditsAdd credits to account
invalid_destinationUse E.164 format (+14155551234)
Check in order:
  1. Verify number is assigned to an application (Console → Phone Numbers)
  2. Check application Answer URL is accessible
  3. Verify Answer URL returns valid Plivo XML
  4. Check for firewall blocking Plivo IPs
Debug steps:
  1. Go to Console → Voice → Logs → Calls
  2. Find the failed call
  3. Check the hangup cause and debug logs
  4. Test your Answer URL manually with curl
Common causes:
  • Firewall blocking RTP/media ports
  • NAT traversal issues
  • Codec mismatch
Solutions:
  1. Whitelist Plivo IP ranges for UDP ports 10000-60000
  2. Enable STUN/TURN if behind NAT
  3. Use standard codecs (G.711, Opus)
See Plivo IP Ranges for whitelisting.
Check hangup cause in call logs:
Hangup CauseMeaningSolution
scheduled_hangupMax duration reachedIncrease time_limit parameter
media_timeoutNo audio for 60 secondsCheck network stability
xml_endNo more XML instructionsAdd more XML or use <Wait>
insufficient_creditsRan out of credits mid-callEnable auto-recharge
IssueLikely CauseSolution
EchoAcoustic feedbackUse headset, reduce speaker volume
Delay/latencyNetwork distanceUse nearest Plivo region
Choppy audioPacket lossCheck internet connection, reduce bandwidth usage
Robotic voiceCodec issuesUse G.711 codec
For persistent issues, capture a PCAP and contact Plivo Support.

​
Step-by-Step Debugging

​
1. Check Call Logs

  1. Go to Console → Voice → Logs → Calls
  2. Find the failed call by time or phone number
  3. Note the Hangup Cause and Hangup Source
  4. Click the call to view debug details

​
2. Verify Configuration

For outbound calls: 
# Test your setup with curl
curl -i --user AUTH_ID:AUTH_TOKEN \
  -H "Content-Type: application/json" \
  -d '{"from": "+14155551234", "to": "+14155559876", "answer_url": "https://example.com/answer"}' \
  https://api.plivo.com/v1/Account/{auth_id}/Call/
For inbound calls:
  • Verify number → application assignment in Console
  • Test Answer URL returns valid XML

​
3. Test Answer URL

Your Answer URL must:
  • Return HTTP 200 status
  • Return Content-Type: application/xml or text/xml
  • Return valid Plivo XML
Example valid response: 
<?xml version="1.0" encoding="UTF-8"?>
<Response>
  <Speak>Hello, this is a test call.</Speak>
</Response>

​
4. Check Firewall Settings

Plivo requires these ports open:
TrafficProtocolPorts
SIP signalingUDP/TCP5060, 5080
Secure SIPTLS5061
RTP (audio)UDP10000-60000
HTTPS callbacksTCP443
See IP Addresses for ranges to whitelist.

​
Common Error Scenarios

​
”Call immediately goes to voicemail”

Possible causes:
  1. Carrier is blocking based on caller ID reputation
  2. Number flagged as spam
  3. Destination has call blocking enabled
Solutions:
  • Register for STIR/SHAKEN attestation
  • Use a different caller ID
  • Contact carrier about spam flagging

​
”API returns 403 Forbidden”

Check:
  1. Account is verified and active
  2. Geo permissions enabled for destination
  3. Caller ID is verified or Plivo-owned
  4. No outstanding balance issues

​
”Calls work sometimes but not always”

Debug steps:
  1. Check if failures correlate with specific destinations
  2. Review call volume vs CPS limits
  3. Check for carrier-specific issues in logs
  4. Monitor for pattern (time of day, destination, etc.)

​
Debug Logs

For detailed debugging, enable debug logs:
  1. Go to Console → Voice → Logs → Calls
  2. Click on the specific call
  3. View the Debug tab for:
    • XML requests/responses
    • SIP signaling details
    • Timing information

​
When to Contact Support

Contact Plivo Support if:
  • Issue persists after following this guide
  • You see internal_error or routing_error hangup causes
  • Calls fail with no clear hangup cause
  • You need PCAP analysis for audio issues
Include in your support request:
  • Call UUID(s)
  • Timestamp of failures
  • Steps already tried
  • Any error messages