Are 0800 numbers free to call on Three (3)?

Yes, 0800-prefixed phone numbers are free to call from UK landline and mobile phones operating on the Three (3) network.

In fact, since 1st June 2015, 0800 and 0808 (freephone) numbers have been completely free to call from all UK landline and mobile phones.

Are all “freephone” numbers free to call from Three phones?

Not exactly. 0800 and 0808 numbers are free to call from Three phones. But 0500 numbers, however, are not always free to call from UK phones – they are still freephone numbers but their use is deprecated – they are being phased out.