Nmber is top right of the reverse side of the Smart card that the actual sim presses out of. You need need to decipher the actual number slightly. Effectively you need the last 9 digits -preceded by +639
or google your phone model for the key sequence that will tell you your number - it varies by phone model.
Bad news is that the sim may need to have been activated for roaming in PI - but I forgot to do that last week & it is still worked in Hong Kong, China & now in UK.