Description

At Telnyx, we have many different situations and settings that can result in a particular SIP response code sent back to your client. We realized that there are so many situations that may result in the same response code, it was necessary to distinguish them so our customers can have further clarity on why some of their calls did not complete as expected.

The aim of this article is to list all the SIP response codes that can be expected and expand on their meaning, along with providing feedback on how to workaround them. We'll also discuss some special cases and include ISDN cause codes and their related hangup reasons.

SIP Response Codes

The format of the response codes is as follows: D1X, D2X, D3X...D9X


These mainly cover 4XX response codes from Telnyx. There is one outlier that is PE1 and will be discussed at the end of this article.

Most of these granular sip response codes can be seen through our conversational product, while some can be seen through our high volume short duration product.

D1X

  • D1 - 403 User channel limit exceeded D1 - The number of concurrent outbound calls for the account is over the limit. This relates to the global account concurrent call limit set in your outbound voice profile section. Should you need this increased, please reach out to our support team.
  • D10 - 403 Forbidden D10 - The outbound call was rejected due to use of a SIP header in your SIP INVITE which is reserved for internal use only. Please reach out to support if this issue occurs so they can advise what header needs to be removed.
  • D12 - 403 Destination Number #{destination_number} is not allowed for service plan #{service_plan} D12 - The destination number is not authorized for the service plan of the OB profile associated with the connection making the call. The customer can change the service plan associated with the OB profile. This is a legacy code and will not be used moving forward. An example is using a legacy service plan such as "US-48/CAN" and attempting to dial Alaska or Hawaii, two states not considered apart of this service plan. The workaround is changing the service plan to International and including America as whitelisted destination in the North American region.
  • D13 - 403 Dialed number #{e164} (pertinent countries: #{pertinent_countries}) is not included in whitelisted countries: #{whitelisted_countries} D13 - The dialed number is not a number from whitelisted countries present in the outbound voice profile associated with the connection making the call. To solve this, the customer can add the dialed numbers country to the whitelist of the given outbound voice profile.
  • D14 - 404 Dialed number is not valid D14 - Simple put, the number dialed is invalid. We ask that the user verify that calls to this number can be reached outside of our network. There is also this great open source tool by google which can be used to validate whether a number is valid or not.
  • D15 - 403 Outbound Profile is disabled D15 - The outbound voice profile associated with the SIP Connection used to place the termination call is not active. Go to your outbound voice profile section and ensure the status of the profile is active and in green. If it is, please refresh the status by toggling it off and back on again.
  • D16 - 403 Connection is disabled D16 - The SIP Connection used to place the termination call is not active. Go to your SIP Connections page and ensure the status of the SIP Connection is active and in green. If it is, please refresh the status by toggling it off and back on again.
  • D17 - 403 Account is disabled D17 - The Account used to place the termination call is blocked. Please contact support so they can investigate the cause for the account block. If your account was blocked, you would have received an email to indicate why.
  • D18 - 404 Not found D18 - The SIP Connection used to receive the origination call is not active. Go to your SIP Connections page and ensure the status of the SIP Connection is active and in green. If it is, please refresh the status by toggling it off and back on again.
  • D19 - 404 Not found D19 - The Account used to receive the origination call is billing blocked. Have you checked that your account is in positive balance, if not please top up your account to ensure services are restored.

D2X

  • D2 - 403 OB profile channel limit exceeded D2 - The number of concurrent calls for the specific outbound voice profile is over the limit. This limit is configurable can be adjusted by customer in their outbound profile settings.
  • D20 - 480 Temporarily Unavailable D20 - The destination number has no SIP connection associated with it. This means that there was an inbound call destined to your number but as there was no SIP connection associated to it, we are unable to route the call to your system. This tends to occur often post port, please ensure that you numbers have SIP Connections assigned to them if you want your system to receive calls.
  • D21 - 480 Temporarily Unavailable D21 - The destination number has no associated destination, no other number to forward to has been found or no IP destinations or crendetial authentication information have been found. This can occur when a SIP Connection is assigned to a number but either the SIP Connection is not registered to our system (if credential based) or the IP's/FQDN's are not set at the DID's routing settings.
  • D22 - 403 Channel limit exceeded D22 - User, outbound voice profile or SIP Connection channel limits have been exceeded. Please increase any channel limits specified on your DID's if using the channel billing method, SIP Connections or Outbound Voice Profiles.
  • D23 - 403 Configuration Error D23 - A general Configuration Error has occurred, please reach out to support for further assistance.
  • D24 - 403 Maximum destination rate limit exceeded D24 - This is when you dial a number in which the rate per minute exceeds the maximum rate per minute set on your outbound voice profile. Please increase the rate per minute on your outbound voice profile settings.
  • D25 - 403 Unable to locate an account/number using IP #{caller_ip} and username #{username} D25 - We are unable to locate account/number with the IP and username used in your SIP INVITE to our system. Please reach out to support for further assistance.
  • D26 - 403 Connection for caller not present D26 - Caller does not have a connection present when attempting outbound calls. Please check that a SIP Connection exists with the username and/or IP from which you are calling, and that it is associated with an outbound voice profile.
  • D27 - 403 Please use siphv.telnyx.com for high-volume traffic calls D27 - This is high volume outbound call traffic and should be sent through siphv.telnyx.com instead of sip.telnyx.com.
  • D28 - 403 IP Address unauthorized D28 - User is unable to authenticate because IP address is unauthorized. When sending traffic high volume traffic to siphv.telnyx.com, please ensure the IP you are sending from is whitelisted in a SIP Connection and associated with an Outbound Voice Profile.
  • D29 - 403 Invalid X-Telnyx-Token #{telnyx_auth_token} or IP #{caller_ip} D29 - The SIP INVITE we received contains an Invalid X-Telnyx-Token with IP. Please ensure the token matches what was set on the expert settings of the SIP Connection. Tokens are used to segregate traffic that come where different SIP Connections share the same IP address.

D3X

  • D3 - 403 Connection channel limit exceeded D3 - The number of concurrent calls for the Connection is over the limit, this limit can be adjusted by the customer in the SIP Connection outbound settings.
  • D30 - 403 Invalid SIP URI calling preference D30 - User SIP URI calling preference cannot be validated. This can apply on both inbound and outbound calls to SIP URI's. Please make sure the SIP URI you are calling is valid.
  • D31 - 403 Invalid SIP Subdomain Receive Settings D31 - This can occur on outbound calls to SIP Subdomains where we were unable to validate the users SIP Subdomain. The user should refresh their SIP Subdomain settings on the SIP Connections inbound settings and retry - otherwise contact support for further assistance.
  • D32 - 488 Only codec g711 or g729 supported D32 - For outbound calls, our high volume short duration outbound profile product supports only g711 and g729. Please ensure you offer only supported codecs, as preference, in your SIP INVITEs SDP to siphv.telnyx.com.
  • D33 - 488 Media encryption not supported D33 - For outbound calls, our high volume short duration outbound profile product does not support SRTP and ZRTP media encryption. Please make sure you remove any media parameters that include encryption in your SIP INVITEs SDP.
  • D34 - 403 Source country is not from EEA D34 - The customers Outbound Voice Profile service plan is set to EEA but the caller ID in the SIP INVITE is not from EEA. This is a legacy code and will generally not be seen anymore as our service plans have since changed on our outbound voice profile offering.
  • D35 - 403 Invalid Caller Origination Number D35 - Caller Origination Number is Invalid. The Caller ID in your SIP INVITE is not valid. Our caller ID policy is explained in more detail here. In short, please make sure your FROM/PAID/RPID headers contain +E.164 number formats.
  • D36 - 403 Forbidden D36 - You are attempting to make an outbound call with a caller ID of a number which belongs to another Telnyx user. Please ensure you use your own DID's as Caller ID on your outbound calls.
  • D37 - 403 Emergency calls not authorized with call control D37 - Emergency outbound calls aren't authorized using our call control product.
  • D39 - 403 International daily spent limit reached D39 - This is a global limit not configurable by account users. It means that your account reached the daily spent limit for international calling. This is a fraud preventative measure. If you require this limit to be increased, please contact support for further assistance.

D4X

  • D4 - 486 User Busy D4 - The number of concurrent calls for the Connection is over the limit, the limit can be adjusted by the customer in SIP Connection inbound settings.
  • D40 - 404 Not Found D40 - For outbound calls, we know the destination exists but we were unable to find a route to connect the call. This usually applies to on-net calling. Please contact support for further assistance so they can advise.
  • D41 - 403 Forbidden D41 - The dialed number matches a prefix that is forbidden to be used. This is a fraud preventative measure, especially for prefixes that are known for revenue sharing and toll pumping. Please contact support for further assistance.

D5X

  • D5 - 486 User Busy D5 - The number of concurrent calls for all numbers under Channel Billing is over the limit. The channel limit can be increased on the Numbers page. More information regarding channel billing is available here.

D6X

  • D6 - 403 Please use sip.telnyx.com D6 - A Conversational call reached siphv.telnyx.com and was rejected. Conversational calls should be routed to sip.telnyx.com instead.

D7X

  • D7 - 403 Connection has no Outbound Profile assigned D71 - The SIP Connection does not have an outbound voice profile associated with it. Please ensure you associate an outbound voice profile in order for calls to be terminated.
  • D71 - 403 Daily OB profile limit exceeded D71 - The daily outbound concurrent call limit has been reached. This is a legacy sip response code and generally won't be seen. Please contact support if you require assistance with this.

D8X

  • D8 - 404 Invalid caller ID number for emergency services D8 - An outbound call towards an emergency number where an valid caller ID number was not provided. Please make sure you use the DID's with E911 enabled on outbound calls toward emergency numbers. This is a legacy sip response code. At this time, we process all calls to emergency numbers but if a caller ID is used that is not a DID on your account or is a DID on your account but without E911 enabled, there will be a surcharge of $100.

D9X

  • D9 - 403 International destination rate limit reached D9 - The international destination rate limit has been reached. This is a legacy SIP response code but may apply when attempting to call the same international number several times within a 60 second period. Please reach out to support to have this limit extended.

PE1

  • PE1 - 503 Service Unavailable PE1 - For outbound calls, we were unable to connect your call as no available routes were found. A 503 is returned in this instance to allow your system to failover to another carrier should you employ back ups. If you do not employ back ups, please reach out to our support team for assistance.

IDSN Cause Codes & Hangup Reasons

ISDN cause codes are used to describe reasons for hang up, they are PSTN based codes which are included in the "Reason" header of SIP response. When the ISDN network or remote user disconnects a call for any reason, the cause might be reported by any ISDN-aware application. They don't necessarily indicate an error as cause codes are shown at the end of normally terminated calls as-well. They are simply guidelines and are implementation-dependent.

An example is: Reason: Q.850;cause=21;text="CALL_REJECTED", where the ISDN cause code is 21 and the hangup reason is call rejected. This generally maps to a SIP 403 response.

Please reference this page which provides a detailed breakdown for each cause code, their relevant hangup reason and associated SIP response mapping.

Special Notes

At this moment in time, and specifically for 488 not acceptable responses, we do not explicitly highlight the reasons for them. We list certain scenarios below where this response code can be seen and why it can occur. At a high level, this error code generally relates to a misconfiguration in your SIP INVITEs SDP, 183 with SDP, 200 OK with SDP, ACK with SDP for late negotiation or a misconfiguration with a setting on your Telnyx account.

Example scenarios in which you may receive this response code if:

  1. You send a re-invite for T.38 on inbound calls but do not have the T.38 fax gateway setting enabled on your DID's expert settings.
  2. You send a re-invite for T.38 on your outbound calls but do not have the T.38 fax setting set to "Customer" or have it set to "Disabled" on your SIP Connections outbound settings.
  3. You send a SIP INVITE with an IPV6 media IP address, something we do not currently support. Please ensure media IP address are IPV4.
  4. You send a SIP INVITE, on your outbound calls, with a codec we do not currently support. For a list of supported codecs, please see this page.
  5. You send a 200 OK, on your inbound calls, with a codec we do not currently support. In this scenario, we'll actually send a BYE with a hangup cause of INCOMPATIBLE_DESTINATION and an ISDN cause code of 88.
  6. You send a SIP INVITE, on your outbound calls, with encryption media attributes in the SDP but have not specified the encryption type on your SIP Connections outbound settings such as SRTP, ZRTP.
  7. You send a SIP INVITE, on your outbound calls, without encryption media attributes in the SDP but have specified the encryption type on your SIP Connections outbound settings such as SRTP, ZRTP. In this scenario, we'll actually send a BYE with a hangup cause of INCOMPATIBLE_DESTINATION and an ISDN cause code of 88.
  8. You send a 183 or 200 OK, on your inbound calls, with encryption media attributes in the SDP but have not specified the encryption type on your SIP Connection inbound settings such as SRTP, ZRTP. In this scenario, we'll actually send a BYE with a hangup cause of INCOMPATIBLE_DESTINATION and an ISDN cause code of 88.
  9. You send a 183 or 200 OK, on your inbound calls, without encryption media attributes in the SDP but have specified the encryption type on your SIP Connection inbound settings such as SRTP, ZRTP. In this scenario, we'll actually send a BYE with a hangup cause of INCOMPATIBLE_DESTINATION and an ISDN cause code of 88.

Final Notes

These errors are subject to change and may be updated in the future.

Most of these errors are self explanatory and following the above workaround suggestions and/or making the appropriate changes or refreshes on your account, will generally resolve these issues.

If you have attempted to resolve these issues but still have difficulty, please contact our support team providing example calls, SIP message logs or SIP Call ID. As a reminder, please leverage your debugging tool which can help provide insight into the SIP logs and the exact responses.

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