Apple iPhone 4 micro-SIM not compatible with iPad

Apple has confirmed in the iPhone FAQ section on its web site that the micro-SIM from the iPhone 4 cannot be used in the iPad.

An iPhone 4 micro-SIM inserted into an iPad will detect that it is not in a smartphone and will not work, according to Nick Wilkins, press relations manager at O2.

"The micro-SIMs for the iPhone are set up to allow voice calls, SMS messages and data functionality, whereas the iPad micro-SIM is provisioned to allow pay-as-you-go data transfer only," he said.

"The two devices are designed to give a different experience. The iPhone 4 is for regular use, whereas with the iPad we offer more flexibility over data use."

The decision will prevent Apple users from carrying over a data allowance from their iPhone to the iPad.

O2 said that it will in time make available a SIM which can be converted back and forth between the micro and regular sizes.

The European Telecommunications Standards Institute oversees SIM cards, and there are three recognised sizes: full, mini and micro. There is no difference in the circuitry, just in the size.

Apple was contacted to ask why the iPhone 4 micro-SIM will not work in the iPad but the vendor had not responded at the time of writing.