If the initial route that is selected by Clickatell's lowest-cost router is delayed due to gateway congestion or for any other reason, the gateway escalation (escalate) parameter will ensure that your message is delivered through alternative routes that support the parameters you have set. This is done by moving through the available gateways in order of increasing cost.
This escalation can continue up to the maximum charge value assigned to the maximum credits parameter, or based on routing profiles selected in your Developers' Central account. When urgent and high priority messages are sent, they should be submitted with escalate set to 1 (one), combined with a high maximum credit value to ensure that the greatest number of gateways are available.
You can view the Parameters list page to see the name of the parameter for the API you are using.