[Serusers] Intermittent Audio

[Greger V. Teigre]

Pat,
You haven't said anything of the type of NAT you are behind. To me it sounds 
like an ALG (Application layer gateway) problem. Try to turn of the SIP ALG 
in your router.  If not, please post a full SIP message exchange.  You need 
to find out if they communicate through the NAT (hairpin media) or directly. 
That depends on the SDP payload in the INVITE and OK messages.
    The new Getting Started document on http://onsip.org/ (you need to 
register) has a thorough review of NAT issues and rewriting. Recommend!  (I 
wrote it ;-) )
g-)

pat newham wrote:
> Following on from my below email, I can now definately
> say the problem is not nat pings. Just to recap I am
> experiencing intermittent audio. It works when the
> phones have very recently registered, then sometimes
> theres one way audio and then sometimes no audio. Does
> anyone have any ideas what the problem could be or
> where I could begin to troubleshoot this?
>
> Hi,
>
> I have a strange problem. I have two grandstream
> budgetone clients on the same subnet behind nat
> registering with ser on a public address. Obviously
> their public addresses would be the same but they
> listen on different ports. When they initially
> register, I can the call,audio is transmitted and
> everything is successful.
>
> However sometimes theres only one way audio, other
> times theres no audio and then other times it
> works....I am guessing that this is because the nat
> router is forgetting the nat mapping so after a while
> when the nat mapping is "forgotten" and a packet
> arrives destined for a client, the router drops it....
>
> Could someone verify this for me??...Am I on the right
> track?? I have the following settings in ser.cfg which
> I thought would keep the nat settings alive.
>
> modparam("registrar", "nat_flag", 6)
> modparam("nathelper", "natping_interval", 30) # Ping
> interval 30 s
> modparam("nathelper", "ping_nated_only", 1)   # Ping
> only clients behind NAT
>
> I also increased the nat keep alives "pings" sent in
> the configuration settings of the grandstream
> phone....Any further ideas??
>
> Regards,
> Pat.
>
> Send instant messages to your online friends
> http://uk.messenger.yahoo.com
>
> _______________________________________________
> Serusers mailing list
> serusers at lists.iptel.org
> http://lists.iptel.org/mailman/listinfo/serusers