select entry in Code column to view full DE allocations in that range
| Code | DEF | Operator | Use | Notes |
| 1200 | Clitheroe | |||
| 1201 | Geographic - unassigned | |||
| 1202 | Bournemouth | |||
| 1203 | Geographic - unassigned (formerly Coventry) | |||
| 1204 | Bolton | |||
| 1205 | Boston | |||
| 1206 | Colchester | |||
| 1207 | Consett | |||
| 1208 | Bodmin | |||
| 1209 | Redruth | |||
| 1210, 1211 | Birmingham National dialling | 3 Digit Area Code | ||
| 1212, 1213, 1214, 1215, 1216, 1217 | Birmingham | 3 Digit Area Code | ||
| 1218, 1219 | Birmingham expansion | 3 Digit Area Code | ||
| 1220, 1221 | Geographic - unassigned | |||
| 1222 | Geographic - unassigned (formerly Cardiff) | |||
| 1223 | Cambridge | |||
| 1224 | Aberdeen | |||
| 1225 | Bath | |||
| 1226 | Barnsley | |||
| 1227 | Canterbury | |||
| 1228 | Carlisle | |||
| 1229 | 0&1 | Barrow-in-Furness National Dialling | ELNS | |
| 1229 | 2 | Barrow-in-Furness | ELNS | |
| 1229 | 3 | Millom | ELNS | |
| 1229 | 4-6 | Barrow-in-Furness | ELNS | |
| 1229 | 7 | Millom | ELNS | |
| 1229 | 8 | Barrow-in-Furness | ELNS | |
| 1229 | 9 | Millom | ELNS | |
| 1230, 1231 | Geographic - unassigned | |||
| 1232 | Geographic - unassigned (formerly Belfast) | |||
| 1233 | Ashford | |||
| 1234 | Bedford | |||
| 1235 | Abingdon | |||
| 1236 | Coatbridge | |||
| 1237 | Bideford | |||
| 1238 | Geographic - unassigned (formerly Saintfield NI) | |||
| 1239 | Cardigan | |||
| 1240 | Geographic - unassigned | |||
| 1241 | Arbroath | |||
| 1242 | Cheltenham | |||
| 1243 | Chichester | |||
| 1244 | Chester | |||
| 1245 | Chelmsford | |||
| 1246 | Chesterfield | |||
| 1247 | Geographic - unassigned (formerly Bangor Co. Down/Kircubbin (Mixed 4/5 Digit Area Code Area) | |||
| 1248 | Bangor (Gwynedd) | |||
| 1249 | Chippenham | |||
| 1250 | Blairgowrie | |||
| 1251 | Geographic - unassigned | |||
| 1252 | Aldershot | |||
| 1253 | Blackpool | |||
| 1254 | Blackburn | |||
| 1255 | Clacton-on-Sea | |||
| 1256 | Basingstoke | |||
| 1257 | Coppull | |||
| 1258 | Blandford | |||
| 1259 | Alloa | |||
| 1260 | Congleton | |||
| 1261 | Banff | |||
| 1262 | Bridlington | |||
| 1263 | Cromer | |||
| 1264 | Andover | |||
| 1265 | Geographic - unassigned (formerly Coleraine/Ballymoney/Ballycastle (Mixed 4/5 Digit Code Area) | |||
| 1266 | Geographic - unassigned (formerly Ballymena/Kilrea/Martinstown (Mixed 4/5 Digit Code Area) | |||
| 1267 | Carmarthen | |||
| 1268 | Basildon | |||
| 1269 | Ammanford | |||
| 1270 | Crewe | |||
| 1271 | Barnstable | |||
| 1272 | Geographic - unassigned | |||
| 1273 | Brighton | |||
| 1274 | Bradford | |||
| 1275 | Clevedon | |||
| 1276 | Camberley | |||
| 1277 | Brentwood | |||
| 1278 | Bridgwater | |||
| 1279 | Bishops Stortford | |||
| 1280 | Buckingham | |||
| 1281 | Geographic - unassigned | |||
| 1282 | Burnley | |||
| 1283 | Burton-on-Trent | |||
| 1284 | Bury-St-Edmunds | |||
| 1285 | Cirencester | |||
| 1286 | Caernarvon | |||
| 1287 | Guisborough | |||
| 1288 | Bude | |||
| 1289 | Berwick-on-Tweed | |||
| 1290 | Cumnock | |||
| 1291 | Chepstow | |||
| 1292 | Ayr | |||
| 1293 | Crawley | |||
| 1294 | Ardrossan | |||
| 1295 | Banbury | |||
| 1296 | Aylesbury | |||
| 1297 | Axminster | |||
| 1298 | Buxton | |||
| 1299 | Bewdley |