$call = new Call();
$call->direction = 'Outbound';
$call->status = 'Planned';
$call->contact_id = $contactid;
$call->duration_hours = '0';
$call->duration_minutes = '15';
$call->date_start = $date; // (mm/dd/yyyy hh:mmTT) format
$call->name = $subjectstring;
$call->assigned_user_id = $current_user->id;
$call->team_id = '1';
$call->team_set_id = '1';
$call->save();
// Create the relationship to Contact to appear in the Contact Subpanel
$contact = new Contact();
$contact->retrieve($call->contact_id);
$contact->load_relationship('calls');
$contact->calls->add($call->id);
Enjoy.