$client = new SoapClient("http://cs2.acme.com/SessionService.svc?wsdl", 
						 array('location' => "http://cs2.acme.com/SessionService.svc/basic"));

$createSessionContextParameters->IpAdress = '127.0.0.1';
$createSessionContextParameters->ClientType = 'web_browser'; 
$createSessionContextParameters->Referrer = '';
$createSessionContextParameters->OperatorOverride = 'abc12345def67';
$createSessionContextParameters->ServiceID = 123;
$createSessionContextParameters->RegionOverride = ''; 
$createSessionContextParameters->LanguageOverride = '';

try{
	$response = $client->CreateSessionContext(array('parameters' => $createSessionContextParameters));
}
catch(SoapFault $fault){
	trigger_error("ERROR: (faultcode: {$fault->faultcode}, faultstring: {$fault->faultstring})", E_USER_ERROR);    
}

$sessionContext = $response->CreateSessionContextResult;

Mockup of how to create a SessionContext using PHP SOAP and ClientServices 2

PHP SOAP CreateSessionContext

php

PHP