On "Who Wants To Be A Millionaire" how many different people were you allowed to have as your "Phone a Friend?"

Contestants may call one of up to five (in some countries' versions, three) pre-arranged friends. In the U.S., the number of pre-arranged friends was three from the introduction of the clock format in September 2008 until the lifeline's elimination from that version in January 2010.

from wikipedia
https://en.wikipedia.org/wiki/Who_Wants_to_Be_a_Millionaire%3F#Original_format

In Indian version we have it as 3.

WWTBAM ran a live show last year and allowed three phone a friends. Rather than the friends being in their own homes, they had to be in the studio and were isolated from the show, presumably so they didn't have a chance to think about the questions for longer than the allotted time. They were also shown live on camera. It somewhat cut out the chance of googling for the answer!

In the Uk there are three phone-a-friend options. In the celebrity shows the 'friends' are in the studio and sometimes are friends for more than one celebrity.