voip firewall rules

Hi there…
am currently in a fix, am using mikrotik to give internet to several voip gateways, the problem is the calls at the gateway are dropping, due to mikrotik firewall configuration… is there a way out of these
thanks in advance

See here:
http://forum.mikrotik.com/t/using-routeros-to-qos-your-network-2020-edition/66683/1