Nothing particular.

The prepaid service uses the Optus GSM network, Australia's 2nd-largest GSM network overall, although the largest in the big population centres of Melbourne and Sydney (and their states Victoria and NSW respectively).

iSim has the cheapest prepaid rates on the market, with a 39c per minute flat rate to most mobiles and landlines anywhere in Australia. This is billed per-second with no connection fee.

GPRS access for WAP is available.

Voicemail is also available (free deposits, flat rate 19c retrieval).

There are no charges for receiving calls on Australian networks, and mobiles have their own area code, i.e. of the form 04xx xxx xxx, which means you can be called on that number anywhere in the country. Mobile-mobile rates are uniform – they do not depend on distance.

You can check your call logs and credits at the iSim website in impressive real-time.

Recharging to a custom amount is done online, or you can SMS or call from the phone to charge a linked credit card.

You can also make overseas calls at reasonable prices, especially to places like the UK, NZ and USA.

There's not a lot bad to say about iSim in terms of usage, its pricing and network service is excellent The main problem is the lack of physical recharge packs, which means a credit card is required.

The customer service is all online however; there is no phone customer service.

None