[Asterisk-Users] Why, why, why???

[Wilson Pickett]

> We have Grandstream SIP phones with the latest firmware versions and
> have also have this problem.  It appears to be something to do with RTP,
> I believe.  I don't know exactly what (simply because I don't know much
> about RTP as yet), but the packets don't seem to reach the Grandstream
> from the other phone.  The phones appear to work correctly when located
> on the same LAN segment.  But, when one is placed behind a NAT router,
> the dynamic changes and one-way audio seems to happen frequently.  I've

Are you forwarding ports? What ports have you set asterisk to? 

IIRC the GS phones come with 8000 by default and asterisk comes with 10000.