Hangup Causes: what code your customer gets

When NEXIA rejects a call, the SIP code it answers decides what the customer's equipment does next: a 503 tells their dialer "try another carrier", while a 486 or 404 is final — the dialer reads it as "this number is dead" and does not retry. Picking the wrong code costs traffic.

Under Settings → Hangup Causes you control exactly which code the switch answers for each rejection reason, with no restart: save and it applies to the next call.

The golden rule

If the call never reached a carrier, the rejection is our problem — not the destination's. That is why every internal rejection (balance, rates, routes, channel caps, account) answers 503 Service Unavailable, which is re-routable: the customer's dialer moves on to its next carrier and their traffic keeps flowing. NEXIA never invents a final code.

And the other way around: if the call did reach a carrier, whatever that carrier answered (486 busy, 404 unallocated, etc.) passes through to the customer as-is. A 486 in your history is a real busy from the destination, not a switch decision. Automatic failover only runs on carrier 5xx or timeout; a carrier 4xx is a definitive answer about that number and is relayed without retrying.

The causes

Category	Cause	What it means
Account	`NEXIA_ACCOUNT_NOT_FOUND`	No customer matches the source IP/credentials.
	`NEXIA_ACCOUNT_DISABLED`	The account is disabled.
	`NEXIA_ACCOUNT_BLOCKED`	The account is blocked.
	`NEXIA_INSUFFICIENT_BALANCE`	The customer's balance is exhausted.
	`NEXIA_BAD_ORIG_PREFIX`	Missing or wrong tech prefix on the inbound call.
	`NEXIA_BLOCKED_DESTINATION`	The destination is on a block list.
Capacity	`NEXIA_CHANNEL_LIMIT`	The customer hit their concurrent-channel cap.
	`NEXIA_OP_CHANNEL_LIMIT`	Origination-point channel cap reached.
	`NEXIA_DP_CHANNEL_LIMIT`	Dial-peer channel cap reached.
	`NEXIA_TP_CHANNEL_LIMIT`	Termination-trunk channel cap reached: the carrier has no free channel right now. Its tariff and rates are fine.
	`NEXIA_TP_CPS_LIMIT`	The termination trunk went over its calls-per-second cap.
Rates	`NEXIA_NO_USER_TARIFF`	The customer has no sell tariff assigned.
	`NEXIA_NO_USER_RATE`	No sell rate covers that destination.
	`NEXIA_NO_PROVIDER_TARIFF`	The outbound trunk has no buy tariff.
	`NEXIA_NO_PROVIDER_RATE`	No buy rate covers that destination.
Routing	`NEXIA_NO_ROUTING_GROUP`	No routing group is configured for that traffic.
	`NEXIA_NO_ROUTE_IN_GROUP`	The group has no peer covering that number.
	`NEXIA_NO_LCR_ROUTE`	LCR found no route.
	`NEXIA_NO_TRUNK_FOR_PREFIX`	No outbound trunk matches the dialled prefix.
	`NEXIA_GW_OFFLINE`	A dial peer covers the number, but none of its gateways is registered or reachable right now.
	`NEXIA_GATE_REFUSED`	The core refused for a policy reason (margin/price rule or a policy module).
	`NEXIA_FAILOVER_EXHAUSTED`	Every candidate carrier was tried and none accepted.

All of them answer 503 out of the box. You can change the code for a specific cause if your operation needs it — the selector only offers valid SIP codes and marks which ones are re-routable.

Where you see it day to day

In Calls → Last Calls, the disposition column shows the compact result — e.g. FAILED (503) — and hovering it shows the breakdown: the exact cause and its explanation, as configured on this page. The per-call ⓘ report carries the same detail.

If a customer reports "you are giving us busy", check the real cause in the history first: a carrier 486 is a real busy at the destination; an internal rejection should never reach them as 486.