020 numbers are not free to call on EE unless you have inclusive minutes on your landline, pay as you go or pay monthly tariff.
020 numbers are used by people and local businesses across the capital city of London, as they are charged at standard rates they are not free to call from an EE handset, unlike the true freephone numbers which start with 0800 and 0808. You will usually pay a set access charge which depends on which EE tariff you are on plus a per-minute rate. However this charge can be avoided if you have inclusive minutes as part of your monthly contract or pay as you go pack.