[Freeswitch-users] Help! FS Unable to Handle Incoming Calls Through SIP Gateway

[Yasuro]

Hi, FreeSWITCH gurus! I need your help!

First off, I am new to FS and I am new to Internet telephony as well.
Heck, I am new to the concept of NAT, UPnP, etc., so please bear with my
ignorance.

I subscribe to a VoIP service at home, with which I get one DID. They
supply me a VoIP adapter. Their expected usage is for you to plug in
analog phones to the analog phone jacks in the VoIP adapter. However, It
also has four Ethernet LAN ports and it acts as a router. You can also
access it from the LAN side and register with its built-in SIP gateway.

What I would like to do is to run FS (Windows version) on one of the
Windows PCs, have it register with the SIP gateway, and have it act as
an AA or IVR. For testing, I am having it just play music.

When I tried the same idea with AsterikWin32, it worked just as I had
hoped; it answered incoming calls automatically. However, I somehow
cannot make it work with FS. I simulate incoming calls to my DID number
with Skype's Sypeout. It fails after a short while with such error
messages as "network error." It appears the call was never answered.

FS is assigned an extension number 7 at the gateway. When I call
extension 7 from a different extension (at the gateway level, not an
extension inside FS), FS does answer the call and I hear music. FS fails
to answer only incoming calls from outside.

I think my FS configuration is fairly standard. I created an external
SIP profile for the gateway under conf/sip_profiles/external/ and
modified conf/dialplan/public/00_inbound_did.xml so incoming calls to
the gateway will be transferred to an extension within FS.

FS's messages and logs, plus the result of packet captures indicate that
FS /thinks /it has answered the call, and goes on to initiate media
communication. I see RTP packets going from FS to the SIP gateway.
What's different from AsteriskWin32's case is that there are no RTP
packets coming back from the SIP gateway to FS. Turning of the firewall
of the PC does not seem to change the result in any way.

For your perusal, I have created the following logs of communication
between FS/AsteriskWin32 and the SIP gateway:

    * AsteriskWin32's case
          o Summary: http://pastebin.freeswitch.org/14457
          o Details: http://pastebin.freeswitch.org/14460
    * FreeSWITCh's case
          o Summary: http://pastebin.freeswitch.org/14462
          o Details: http://pastebin.freeswitch.org/14463
          o Log: http://pastebin.freeswitch.org/14465

The IP address of the SIP gateway is *192.168.11.250*, and that of the
PC FS/AsteriskWin32 resides in is *192.168.11.11*. My DID number is
masked as ABCDEFGHIJ. I do not know if it gives you any useful
information, but those files include the registration phase. /FS's log
was taken at a different time/, so it does not entirely match the packet
captures.

I also have the corresponding Pcap files. Please let me know if you need
them.

I am not entirely sure, but I think as far as what I'd like to do is
concerned, NAT is not going to be an issue, because the FS/AsteriskWin32
PC and the SIP gateway (its LAN side IP address) are on the same subnet
(192.168.11/24). At this time, I do not need to access FS from the Internet.

Finally, I will give you more details about my setup, which may or may
not be relevant to this issue.

My home LAN is set up this way:
http://i139.photobucket.com/albums/q302/starplatina/For%20Blogs/HomeLANSetup.jpg
Please note that there are /two layers/ of NAT, and that in the inner
layer, two NAT devices exist. I know it looks convoluted, but there are
logical reasons for this setup.

The VoIP service provider only supports the PCMU codec. The music file I
prepared for this testing is encoded in PCMU, so codecs will not be an
issue.

Please do not hesitate to ask if you have any questions. Thanks for your
help in advance!

Yasuro


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