As most Dutch area codes have changed since the BBS-era, the country code (31) is best suited for BBSes (formerly) located there.
Costs of calling a BBS in the NetherlandsEdit
A phone-call in the Netherlands (and therefor a call to a BBS) was always charged in time-units costing 15 cents each. This system was derived from mechanical counters that would 'tick' every few minutes for a call, depending on distance. There was an area near your own 'area code' called 'basistariefgebied' which had the lower rate. This influenced your choice in BBSes. Most BBS users knew the area codes of their 'basistariefgebied' by heart (and still had a shocking phonebill).
In 1985 unlimited local calls for one 'tick' were stopped. The rise of modems and BBSes is thought to have played a part in the decision to stop offering unlimited length local calls for a fixed price.
The big renumbering (operatie Decibel)Edit
On 10-10-1995, after long preparations the phone numbers in the Netherlands changed from variable length (8-10 digits) to all 10-digit dialing with space for number ranges for potential new operators.