SIM data usage is more often than not controlled by the customer through their hardware solution. There are many factors which can influence the quantity of data transmitted and hence received, but how the customer configures their hardware to transmit via the SIM is the biggest determinant of how much data will realistically be used. That being said, there is always a slight doubt as to what the hardware is capable of meaning that data usage could spiral out of control at any point.
Airtime agreements specify the limits for data usage, encapsulated by a data bundle. The data bundle is what the customer should gauge said usage against. Any additional usage above this pre-agreed bundle amount will be charged at the rate agreed in the contract.
Over the public APN, usage can be stopped by applying a high usage bar on the SIMs at network level. Please note this only applies to UK based SIMs (Vodafone, EE and O2). Telenor and Aspider allow the application of an alert when the SIM breaches its contracted allowance. However, the SIM will still remain active and will transmit data until it is deactivated.
Over the private APN, usage can be blocked of via the application of a quota. Data quotas specify an upper limit, which when breached, will completely cut off the SIM until it is requested to be lifted or extended. As well as the quota, alerts can be applied at any point so there is knowledge prior to the quota being exceeded for example. This allows the best management as the quota can be removed upon reception of this alert or appropriate action can be taken to allow the SIM to continue working.
Please note, customers who would like to use the private APN will be required to purchase Concirrus SIMSafe. Find out everything you need to know about the hosted VPN in the cloud here.