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Call Status and Bye Reason

Call Status refers to the different states or conditions that a call may go through during its lifetime. These states could include call ended, declined, busy, not answered, cancelled, abandoned, unreachable, or call failed, among others.

Bye Reason, on the other hand, explains why a call has been disconnected. When a call is disconnected, the party initiating the disconnection sends a BYE message, which may include a reason code to explain the cause. Some of these reasons could consist of the user hanging up, network or service congestion, bearer capability not authorised or available, and outgoing or incoming calls barred, among others.

Call Status

The Call Status page provides a helpful and informative resource for users who encounter different call statuses during call communication.

The Call Status provides a comprehensive list of statuses that could be encountered when making a call, along with their respective definitions. This will serve as a reference to help understand the Reason behind a specific call status and how it ended. Each status is accompanied by a definition explaining what it means and what actions the user can take in response.

Call Status Definition
Call Ended * Call connected and completed (e.g., normal clearing - ended by caller/receiver). * Call connected and dropped (e.g., network issue, service congestion, unspecified error).
Declined The receiver rejected the call.
Busy The receiver is unable to accept another call.
Not Answered The receiver did not respond and timed out.
Cancelled The ongoing call hung up before the person on the other end (receiver) picked up.
Abandoned The call was established to the receiver; however, * The caller hung up while in the IVR menu. * The caller hung up while the voicemail was on. * The caller hung up while on hold with a staff member during the call transfer.
Unreachable The caller cannot reach the receiver due to the following reasons: * The receiver's device is turned off * The receiver has no data connection * The receiver was out of the coverage area * Service temporarily congested
Called Failed In general, the call failed due to service and network-related issues.

Last Response Code & Bye Reason

The Last Response Code and Bye Reason table shows the reasons behind specific call disconnections. The table lists different codes and their respective definitions, including an explanation of the corresponding bye reason.

Last Response Code Bye Reason Definition
N/A UNSPECIFIED Unspecified. No other cause codes are applicable.
403 OUTGOING_CALL_BARRED This China Unicon Global (CUG) member was not allowed to make outgoing calls.
403 INCOMING_CALL_BARRED Incoming calls were not allowed to this member of the CUG.
403 BEARERCAPABILITY_NOTAUTH The user has requested a bearer capability implemented by the equipment, but the user was not authorised to use it.
403 BEARERCAPABILITY_NOTAVAIL The user has requested a bearer capability that is implemented by the equipment, but it was not available at this time.
404 UNALLOCATED_NUMBER Unallocated (unassigned) number.
404 NO_ROUTE_TRANSIT_NET No route to the specified transit network. (National use)
404 NO_ROUTE_DESTINATION No route to a destination.
408 NO_USER_RESPONSE No user is responding.
410 NUMBER_CHANGED Number changed.
410 REDIRECTION_TO_NEW_DESTINATION The call was redirected to a new destination.
480 NO_ANSWER No answer from the called party or receiver.
480 SUBSCRIBER_ABSENT Subscriber absent.
483 EXCHANGE_ROUTING_ERROR The destination indicated by the user cannot be reached
484 INVALID_NUMBER_FORMAT Invalid number format. (Address incomplete)
486 USER_BUSY User busy.
487 ORIGINATOR_CANCEL If a visitor made a PSTN call and cancelled it.
488 INCOMPATIBLE_DESTINATION The equipment sending this cause has received a request to establish a call with low-layer compatibility, high-layer compatibility or other compatibility attributes (e.g. data rate) that cannot be accommodated.
488 INVALID_MSG_UNSPECIFIED Invalid message, unspecified
488 MANDATORY_IE_MISSING The equipment sending this cause has received a message missing information that must be present for the message to be processed.
488 MESSAGE_TYPE_NONEXIST The equipment sending this cause has received a message with a message type it does not recognise because it is not defined or implemented by the equipment sending this cause.
488 WRONG_MESSAGE The equipment sending this cause has received a message that the procedures do not indicate was a permissible message to receive. In contrast, a STATUS message was received in the call state, suggesting that it was in an incompatible call state.
488 IE_NONEXIST The equipment sending this cause has received a message that includes information element(s) or parameter(s) not recognised because the information element(s) or parameter name(s) were not defined or were defined but not implemented by the equipment sending the cause.
488 INVALID_IE_CONTENTS The equipment sending this cause has received the information element it has implemented; however, one or more fields in the information element were coded in a way that has not been implemented by the equipment sending this cause.
488 WRONG_CALL_STATE The message was received when the message was incompatible with the call state.
488 BEARERCAPABILITY_NOTIMPL The equipment sending this cause does not support the bearer capability requested.
488 CHAN_NOT_IMPLEMENTED The equipment sending this cause does not support the channel type requested
501 FACILITY_REJECTED Facilities rejected.
501 FACILITY_NOT_IMPLEMENTED The equipment sending this cause does not support the requested supplementary services.
501 SERVICE_NOT_IMPLEMENTED Service or option not implemented, unspecified
502 DESTINATION_OUT_OF_ORDER Destination out of order
502 NETWORK_OUT_OF_ORDER The network is out of order
503 NORMAL_CIRCUIT_CONGESTION No circuit or channel is available.
503 NORMAL_TEMPORARY_FAILURE The network did not function correctly.
503 SWITCH_CONGESTION Switching equipment congestion.
503 REQUESTED_CHAN_UNAVAIL The other side of the interface cannot provide the circuit or channel indicated by the requesting entity.
504 RECOVERY_ON_TIMER_EXPIRE The expiration of a timer in association with error handling procedures has initiated a procedure.
603 CALL_REJECTED The call was rejected.
901 Terminated_From_Server The call was cancelled on the server side.
902 Abandoned_IVR_Menu The caller hung up from the IVR menu.
903 Abandoned_On_Hold The caller hung up the call while the call was on hold with an agent (e.g., Call Transfer).
904 Abandoned_Voicemail The caller hung up while the call was on voicemail.
905 Caller_Left_Voicemail The caller left a voicemail after hanging up the call.
906 End_In_IVR The caller hung up the call while the call was in the IVR menu.
907 Transferred_From_IVR The caller selected the call transfer option inside the IVR menu and transferred the call to the configured destination (Agent)
908 Ended_In_Call_System The call was hung up while it was in the ACD greeting prompt mode, before the agent could pick up.
909 Transferred_From_Call_System The Automatic Call Distribution (ACD) system started distributing the call to an agent to answer.
FACILITY_NOT_SUBSCRIBED The user requested a supplementary service, which was available, but they were not authorised to use it.
RESPONSE_TO_STATUS_ENQUIRY Response to status inquiry.
SERVICE_UNAVAILABLE Service or option not available.
INVALID_CALL_REFERENCE The equipment sending this cause has received a message with a call reference which was not currently in use on the user-network interface.
MANDATORY_IE_LENGTH_ERROR The equipment sending this cause has received a message that includes parameters not recognised because they were not defined or were defined but not implemented by the equipment sending this cause.
PROTOCOL_ERROR This cause was used to report a protocol error event only when no other reason in the protocol error class applies.
INTERWORKING This cause indicates that an interworking call (usually a call to the SW56 service) has ended.
MANAGER_REQUEST This cause was used when you sent an API command to make it hang up. For example uuid_kill <uuid>
BLIND_TRANSFER The blind transfer was taken to the call.
ATTENDED_TRANSFER The warm transfer was taken to the call.
PICKED_OFF The call was picked up by intercepting it from another extension (i.e. dialling the ext_number from another extension).
USER_NOT_REGISTERED You tried to originate a call to a SIP user who forgot to register.
PROGRESS_TIMEOUT The call progress exceeds the time limit.
GATEWAY_DOWN The gateway was down (not answering on OPTIONS or SUBSCRIBE)
Abandoned_Voicemail The caller hung up while the call was on voicemail.
CALL_FORWARD The call was forwarded to a PSTN Number.
CHANNEL_UNACCEPTABLE Channel unacceptable.
CALL_AWARDED_DELIVERED The call is being delivered in an established channel.
NORMAL_CLEARING Normal call clearing.
ACCESS_INFO_DISCARDED The network could not deliver access information to the remote user.
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Last modified: 2025-12-08