Call Disposition Statuses explained [Call outcomes and hang-up causes]

Call Disposition Statuses

Nimbata assigns a call disposition status to every call attempt based on standard telephony signaling (ITU-T Q.850 and SIP responses). These statuses describe how a call ended at the network level. They are useful for:

Troubleshooting failed calls
Understanding routing behavior
Building filters or automations
Interpreting webhook data

The default signaling code for successfully connected calls is NORMAL_CLEARING.

Note: Disposition statuses reflect the telephony outcome of a call attempt. They do not always indicate a business outcome (e.g., whether the call was a qualified lead). Always review call duration, recordings, call flow setup, and routing when diagnosing issues.

Below is a breakdown of common call disposition statuses you may see in your reports, webhooks, or automations.

ITU-T Q.850 Code	SIP Equiv.	Enumeration	Cause	Description
0		UNSPECIFIED	Unspecified. No other cause codes applicable.	This is usually given by the router when none of the other codes apply. This cause usually occurs in the same type of situations as cause 1, cause 88, and cause 100.
1	404	UNALLOCATED NUMBER	Unallocated (unassigned) number \[Q.850 value 1\]	This cause indicates that the called party cannot be reached because, although the called party number is in a valid format, it is not currently allocated (assigned).
16		NORMAL CLEARING	Normal call clearing \[Q.850\]	This cause indicates that the call is being cleared because one of the users involved in the call has requested that the call be cleared. Under normal situations, the source of this cause is not the network. A NORMAL_CLEARING status indicates that the call ended normally at the network level. It does not confirm call quality, duration, or business outcome.
17	486	USER BUSY	User busy \[Q.850\]	This cause is used to indicate that the called party is unable to accept another call because the user busy condition has been encountered. This cause value may be generated by the called user or by the network. In the case of user determined user busy it is noted that the user equipment is compatible with the call. This status may be generated by the recipient’s device, the carrier, or the network and does not indicate a configuration issue in Nimbata.
18*	408	NO USER RESPONSE	No user responding \[Q.850\]	This cause is used when a called party does not respond to a call establishment message with either an alerting or connect indication within the prescribed period of time allocated.
19*	480	NO ANSWER	No answer from user (user alerted) \[Q.850\]	This cause is used when the called party has been alerted but does not respond with a connect indication within a prescribed period of time. Note - This cause is not necessarily generated by Q.931 procedures but may be generated by internal network timers.
21	603	CALL REJECTED	Call rejected \[Q.850\]	This cause indicates that the destination did not accept the call, even though it was technically reachable. The rejection may be triggered by the recipient’s device, the network, or service-level restrictions. It does not always mean the end user manually declined the call.
28	484	INVALID NUMBER FORMAT	Invalid number format (address incomplete) \[Q.850\]	This cause indicates that the called party cannot be reached because the destination number is not in a valid or complete format. This usually indicates a formatting or configuration issue with the destination number (e.g. missing country code or incomplete number).
41**	503	NORMAL TEMPORARY FAILURE	Temporary failure \[Q.850\]	This cause indicates that the network is not functioning correctly and that the condition is not likely to last a long period of time; e.g. the user may wish to try another call attempt almost immediately.
63**		SERVICE UNAVAILABLE	Service or option not available, unspecified \[Q.850\]	This cause is used to report a service or option not available event only when no other cause in the service or option not available class applies.
487	487	ORIGINATOR CANCEL		The caller initiated the call and hung up before the destination answered. This commonly occurs when the caller cancels quickly or during simultaneous dialing setups.
502		LOSE RACE		This occurs when multiple destinations are dialed simultaneously (e.g. using the Dial call action). Once one destination answers, the remaining call attempts are terminated with a LOSE_RACE status. This is expected behavior and does not indicate an error.
604		MEDIA TIMEOUT		Media negotiation or transmission did not complete within the expected time. This may be caused by network instability, firewall restrictions, or carrier-level media negotiation issues.

Understanding signaling vs. business outcome

A call disposition status tells you how the call ended technically, not whether it was a qualified lead, a missed opportunity, or a completed sale. For example:

A call may have NORMAL_CLEARING but last only 3 seconds
A call may show NO_ANSWER even though your routing was correct

Always evaluate disposition statuses together with:

Call duration
Call recordings
Call flow logic
Destination number configuration

When should you investigate?

Occasional failures are normal in telephony networks. Investigate when you notice:

A sudden spike in failures
Repeated INVALID_NUMBER_FORMAT errors
Persistent SERVICE_UNAVAILABLE or TEMPORARY_FAILURE statuses
Calls not reaching your destination numbers

In these cases, review your call flow setup and contact support with:

Example call IDs
The tracking number used
The destination number configured

*Note: NO USER RESPONSE typically means the call did not reach a ringing state. NO ANSWER means the call rang but was not answered.**Note: These statuses typically indicate transient network conditions and may resolve without changes to your setup.

For troubleshooting failed calls, use disposition statuses together with call flow and tracking number configuration for a complete picture.

Updated on: 13/02/2026

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