Login problem

Why all the phones behind the router can’t login ?
the setting for firewall is all open.
do i need to setup any what stun,… server to cope with the router , firewall login problem ?

Sip is buggy at best,

look for setting in router(s)
Stateful Packet Inspection Turn it off…

Try to force the phones on higher ports 5061 bah bah
one on 5060
second on 5061
third on 5062
so on (with more than two cisco ATA on a network I get better results doing this.

go iax software phone and test your system (only needs to have the port 4569 forward to the server, nothing on other end in most cases (even works with SPI on)