Messages are accepted but not arriving
Every call returns success. Work through this in order — the first four checks do not involve the carrier at all.
Read this article →A provider stopped accepting traffic
Telling an account-level failure apart from a bad route, and what failover can and cannot absorb for you.
What it looks like
Failures rise suddenly and cluster: sends that went through fine yesterday now come back rejected, while a second connected account keeps working. That contrast is the signal — the problem is attached to one connection, not to your content.
Account-level, or route-level?
- Naming the credentials — the account-level problem. Something changed on the provider side: a rotated key, a suspended account, a quota exhausted.
- Naming the sender — the sender identity is no longer authorised. Registration, verification or a carrier filter is the likely cause, and it is resolved with the provider.
- Naming the destination — the route to a country or network is refusing this sender type. Every account may hit the same wall, so failover will not help.
What failover does, and what it does not
Automatic failover moves traffic to another connected account on the SMS channel, which absorbs an account-level failure without you intervening. It cannot absorb a route-level failure: if the rejection is attached to the destination rather than to the account, there is nothing for failover to route around.
Note. Automatic failover between connected accounts is implemented for the SMS channel and is not claimed for the email or WhatsApp channels.
Working through it
Read the error codes per connection
The log records the provider’s raw error. Compare a failing account against a working one.
See whether failures cluster by destination
Clustered by destination points at a route or a registration; spread across destinations points at the account.
Check whether traffic already moved
If another account is carrying the volume, failover is working and your remaining task is the account that failed.
Fix the underlying cause with the provider
The platform cannot lift a carrier filter, restore a suspended account or renew a registration.
Keep reading
Messages that fail with an error code
A failed status always carries a reason. The first question is which layer wrote it — the platform or the provider.
Read this article →A recipient received the same message twice
Almost always this is a client-side timeout followed by a resend. Here is how to confirm it, and how to stop it happening.
Read this article →