Allow post-paid clients to set unlimited calls (No credit limit)

function get_balance(userinfo)
	balance = (userinfo['balance']) + (userinfo['credit_limit'] * userinfo['posttoexternal']);    
-- Override balance if call is DID / inbound and coming from provider to avoid provider balance checking upon DID call. 
    if (userinfo['type'] == '3' and call_direction == 'inbound') then            
            balance = 10000
    end   
    -- Make Postpaid calls unlimited if credit limit set to 0. 
    if (userinfo['posttoexternal'] == '1' and userinfo['credit_limit'] == '0.00000') then            
	 balance = 10000
    end   

    return balance
end