Outbound messages will be labeled as "failed" with Plivo error code 900 and will not be forwarded to downstream carriers. For the next two minutes after we generate this error code, all send message API requests will fail with the error "Insufficient Credit." This is to let you take action before queuing more messages.
All messages that are already queued in Plivo's system will continue to be marked "failed" with error code 900 as and when they are dequeued for processing until you add the necessary credits to the account.