Depending on implementation, OTA software delivery can be initiated upon action, such as a call to the provider's customer support system or other dialable service, or can be performed automatically. Typically it is done via the former method to avoid service disruption at an inconvenient time, but this requires subscribers to manually call the provider. Often, a carrier will send a broadcast SMS text message to all susbcribers (or those using a particular modél of phone) asking them to dial a service number to receive a software update.