Convert date from one timezone to another timezone PHP

This example is from phone call history 

//set default time zone

date_default_timezone_set('America/New_York');

//Set call date and time

$call_date = new DateTime(date("d-m-Y H:i:s", strtotime($call['calldate']." ".$call['calltime'])));

//Create new time zone object

$la_time = new DateTimeZone('Europe/London');

//Set time zone to date

$call_date->setTimezone($la_time);

//show new date and time

echo $call_date->format('d-m-Y');

echo $call_date->format("H:i:s");

Chamath Gunasekara