03 numbers are a UK-wide local number charged at a local rate. These are also known as local or geographic numbers and can be called from a landline or mobile.
03 numbers are typically low-cost and most UK mobile phone plans have 03 numbers included in their calling package, which makes it free to call these types of numbers. To check whether it's free for you or not it's best to call your phone provider.
With Powwownow, we offer 03 numbers to our Extras and Premium customers. This makes conference calling a lot more cost effective if you're dialling in from the UK (particularly if it's included in your mobile phone plan).
When it comes to conference calling, 03 numbers are paid for by the host, whereas 0844 numbers are shared cost numbers. Shared cost numbers mean that each participant pays their own part of the call.