SIP Response Codes
Reference of SIP response codes you’ll see on Telnyx SIP Trunking calls — 4xx client errors, 5xx server errors, 6xx global failures, and what they mean.
Telnyx-specific SIP response codes for diagnosing call failures.
Documentation Index
Fetch the complete documentation index at: /llms.txt
Use this file to discover all available pages before exploring further.
Check out our upcoming events and meetups! View events →
Reference of SIP response codes you’ll see on Telnyx SIP Trunking calls — 4xx client errors, 5xx server errors, 6xx global failures, and what they mean.
| Code | SIP Status | Description | Resolution |
|---|---|---|---|
| D1 | 403 | Concurrent outbound calls exceed global limit | Reduce active calls or increase limit in outbound voice profile |
| D10-D17 | 403 | Connection, profile, or account disabled/forbidden | Verify SIP connection and outbound voice profile are active |
| D18 | 404 | SIP connection inactive | Enable the SIP connection |
| D19 | 404 | Account blocked (billing) | Review account balance and payment method |
| Code | SIP Status | Description | Resolution |
|---|---|---|---|
| D2 | 403 | Outbound profile concurrent call limit exceeded | Reduce active calls or increase profile limit |
| D21 | 480 | No destination/forwarding number associated | Verify destination number is valid and active |
| D22 | 403 | Channel limit exceeded (DID, connection, or profile) | Check channel allocations |
| D24 | 403 | Rate per minute exceeds profile maximum | Adjust rate limits in outbound voice profile |
| D25-D29 | 403 | Authentication or connection validation failed | Verify SIP credentials and connection settings |
| Code | SIP Status | Description | Resolution |
|---|---|---|---|
| D3 | 403 | Connection concurrent call limit exceeded | Reduce active calls or increase connection limit |
| D30-D31 | 403 | Invalid SIP URI or subdomain | Verify SIP URI format and subdomain settings |
| D35 | 403 | Invalid caller ID format | Use E.164 format (e.g., +12125551234) |
| D36 | 403 | Using another account’s DID as caller ID | Use only assigned phone numbers |
| D38 | 403 | No outbound voice profile assigned to connection | Assign an outbound voice profile |
| Code | SIP Status | Description | Resolution |
|---|---|---|---|
| D40 | 404 | Destination exists but no route available | Verify destination and routing configuration |
| D41 | 403 | Dialed prefix forbidden (fraud prevention) | Contact support to enable destination |
| D42 | 405 | SIP REFER not allowed | Enable call transfer in connection settings |
| D49 | 403 | NANPA origination number lacks valid LRN | Ensure phone number has LRN data |
| Code | SIP Status | Description | Resolution |
|---|---|---|---|
| D5 | 486 | Legacy channel billing limit exceeded | Review channel billing settings |
| D51 | 403 | Non-Telnyx number not verified | Use Verified Numbers API |
| D52-D54 | 403 | Restricted origination number | Verify number ownership and status |
| D56 | 486 | Global channel billing limit exceeded | Contact support |
| D57 | 403 | HD voice disabled for phone number | Enable HD voice in phone number settings |
| D59 | 404 | Special/short number unsupported by region | Use supported number type |
| Code | SIP Status | Description | Resolution |
|---|---|---|---|
| D60-D61 | 403 | Account tier requires verified numbers | Upgrade account tier or verify numbers |
| D63 | 403 | Number port pending | Wait for port completion |
| D64-D65 | 403 | Regulatory requirement pending | Complete regulatory documentation |
| Code | SIP Status | Description | Resolution |
|---|---|---|---|
| D7 | 403 | No outbound voice profile assigned | Assign an outbound voice profile |
| D8 | 404 | Missing E911 caller ID | Configure E911 caller ID |
| D9 | 403 | International destination rate limit reached | Review rate limits or contact support |
| Code | SIP Status | Description | Resolution |
|---|---|---|---|
| P01 | 403 | Invalid Request-URI (proxy anycast IP) | Use correct contact header |
| P02 | 403 | CANCEL without matching INVITE | Only send CANCEL for active INVITE transactions |
| P04 | 403 | REGISTER with To tag (RFC non-compliant) | Remove To tag from REGISTER requests |
| P05-P06 | 403 | CPS limit or message size exceeded | Reduce call rate or message size |
| P14-P16 | 403 | Contact header length violation | Shorten contact header to under 512 bytes |
| P18 | 403 | Empty destination in Request-URI or To | Include valid destination in SIP headers |
| P29 | 500 | REGISTER processing failure | Retry registration or contact support |
| P51 | 403 | Contact header exceeds 512 bytes | Reduce contact header length |
| P81-P83 | 403 | Username validation issues | Verify SIP username format |
| P93 | 403 | Hop count exceeded | Check for routing loops |
| Code | SIP Status | Description | Resolution |
|---|---|---|---|
| R14 | 403 | Empty authentication username | Provide valid SIP username |
| R16-R18 | 403 | Invalid/short/mismatched username | Use alphanumeric username matching credentials |
| R47 | 403 | Multiple Contact addresses in REGISTER | Register one contact address per request |
| RG1 | 480 | User not registered (credential connection) | Register SIP client before making calls |
| Code | SIP Status | Description | Resolution |
|---|---|---|---|
| PE1-PE6 | 503 | No routes found | Verify destination is reachable |
| Code | SIP Status | Description | Resolution |
|---|---|---|---|
| TV1 | 503 | Downstream carrier termination issue | Retry call or use alternative routing |
| TM1 | 403 | No rates for destination prefix | Contact support about coverage |
| Code | SIP Status | Description | Resolution |
|---|---|---|---|
| B3 | 488 | SRTP mismatch - encrypted media expected | Enable SRTP in SIP client or disable in connection |
| Scenario | Resolution |
|---|---|
| Private IP in SDP | Use public IP addresses |
| T.38 fax mismatch | Verify T.38 settings match |
| IPv6 media addresses | Use IPv4 (IPv6 not supported) |
| Unsupported codecs | Use G.711, G.722, G.729, or Opus |
| SDP encryption conflicts | Ensure consistent SRTP settings |
Was this page helpful?