Portishead comes under the Bristol area code, which is 0117.
Local numbers are 7 digits long, so a Portishead number would be of the form: (0117) xxx xxxx.
This is wrong, Portishead is 01275 which cover most of this North Somerset Area (Clevedon, Pill, Nailsea, Chew Magna, Flax Bourton, Long Ashton and Lulsgate). Local numbers are 6 digit