How to set ice server in mongooseim.cfg

[maguon]

MongooseIM version 3.5.0
MongooseICE version 0.4.0
MongooseICE has been start with port 3478.
udp 0 0 127.0.0.1:3478 0.0.0.0:*

I found the ejabberd_stun options in mongoose.cfg,but I don't know how to set it.
%%,{ {3478, udp}, ejabberd_stun, []}

I try to find some tips in source code ,but souce code have no "ejabberd_stun" .

[maguon]

mongooseimctl live
I found notice in log :
16:29:03.729 [notice] Skipping STUN stun.voxgratia.org
16:29:03.729 [notice] STUN could not find external IP!!

but when I execute the command mongooseimctl live
I found the stun notice is different with last time.
16:33:13.482 [info] Checking STUN stun.freeswitch.org
:0: Warning: export_all flag enabled - all functions will be exported

why the stun server has been changed .

Thanks.