"You are being summoned by <Original summoned stone players name> Do you accept?" Yes/No.
I just had a hardcore Demon Soul Dark Soul flash back... XD
Soul Signs ftw :P - I'd hope they can reduce the amount of free teleports per zone with this idea, but I like this idea either way. A nice way for a large parties waiting for an extra to get going faster

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Can stop this: "White mage left, everyone take an hour break" lol
@Zenaku
I dont think this should be relegated to only Free Companies because then it encourages you to not party outside of your group - more elitism kind of nonsense.
Also to answer why a person wouldn't just teleport to location and walk I think its made fair by the fact it needs 3 people already in location.
Its good when you are far in a camp and you cant get out easily without that extra person. Could put a summon debuff on the summoners (or just the main summoner) too so that you need 3 different people each time you want to summon one person (to prevent 3 people summoning an army).
Also for the summon action can I recomend WoW's system? You just right click on the portal to support it, easier and less obtrusive XD.