Yes you can, If you are calling within UK, the call is free of charge. But if you are calling 800 abroad, the charge for the call is the same as making an international call.
Just dial the number that has that letter on the key. 2 = ABC 3 = DEF 4 = GHI 5 = JKL 6 = MNO 7 = PQRS 8 = TUV 9 = WXYZ Thus, the first widely advertised "vanity" number, 1-800-FLOWERS, is really...