@SUN: Even if one gets Yahoo Plus, messenger problem in AT&T would not be solved till service book file is present in the phone.
Yahoo Messenger DOES NOT require Premium Yahoo Account. Its an old problem with AT&T Blackberry phones, as Yahoo Messenger requires specific service book file given in the link above which is not there by default in AT&T phones.
P.S:
I was able to setup Free Yahoo Mail because I am a Power User of Yahoo Mail, otherwise, Yahoo Mail on Blackberry does require Yahoo Plus account but not for Messenger.
@SUN: Even if one gets Yahoo Plus, messenger problem in AT&T would not be solved till service book file is present in the phone.
Yahoo Messenger DOES NOT require Premium Yahoo Account. Its an old problem with AT&T Blackberry phones, as Yahoo Messenger requires specific service book file given in the link above which is not there by default in AT&T phones.
P.S:
I was able to setup Free Yahoo Mail because I am a Power User of Yahoo Mail, otherwise, Yahoo Mail on Blackberry does require Yahoo Plus account but not for Messenger.