In regards to the separate rule of Muslims in both Spain and the middle east , the Islamic campaign that marched upon Spain was sent by the Umayyads. However , during the Muslims conquest in Spain , the Ummayads rule ended by the hands of the Abbasids. So initially it wasn't a separate rule.
However , a Caliphate is a successor. But it also means ' heir '. So if we're going for a literal explanation , the first ruler of the Abbasids cannot be called a Caliphate , since he took the rule from the Umayyads by force. But the next Abbasids ruler can be called a Caliphate which means ' and heir '.
But in a modern sense , there can't be a Caliphate. Simply because every country has its own rules , borders , constitution ... etc. So in order for a Caliphate to happen , a country has to relinquish its rule to that Caliphate , and act as a governor under the rule of the Caliphate ... You let me know when a country would agree to that.
As for ISIS , they are self-proclaimers. So whatever they say means diddly squat since they aren't recognized by most Muslims.
On a side note , ISIS in the last three months has taken the habit of sending suicide bombers to bomb mosques in Saudi Arabia and Kuwait during prayer times. So ... yeah , they're not Muslims.