t come from cc_callerid table but if you change it in database only you'll have problem as i can tell you that,
have look into Class.A2Billing.php from line 2335
this is one example, and now there are other places where you have to change that t to yes
Code:
if ($this->agiconfig['cid_sanitize']=="CID" || $this->agiconfig['cid_sanitize']=="BOTH") {
$QUERY .= "SELECT cc_callerid.cid ".
" FROM cc_callerid ".
" JOIN cc_card ON cc_callerid.id_cc_card=cc_card.id ".
" WHERE (cc_callerid.activated=1 OR cc_callerid.activated='t') AND cc_card.username='".$this -> username."' ";
or you can manipulate that t to yes on display, let us know how you get on with this.