What is the telephone area code for Ibiza Spain?

Spain no longer uses area codes, per se. You must dial the full nine-digit national number for all calls within Spain, and country code +34 followed by the 9-digit national number for international calls into Spain. However, landline numbers in Ibiza and the Balearic Islands most likely begin with either 971 or 871.

Mobile phone numbers throughout Spain begin with 6 or 7.

(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)