<?php
//following GMT value or offset get from api
$offsetHours = '-5 hours';
// This time i get from api
$currentValue = '1401705628';
$actualTimeStamp = strtotime($offsetHours,$currentValue);
echo strtotime($offsetHours)."===";
echo $actualTimeStamp."===";
echo date('d-M-Y h:i A',$actualTimeStamp);
echo "==mk="mktime(-5, 0, 0, 0, 0, 0);
echo "===".date("d-M-Y h:i A", $currentValue+mktime(-5, 0, 0, 0, 0, 0));