No Voice on Samsung IP Phone Outside of Network

Hello Experts,

We recently picked up a client who is using a Samsung OfficeServ 7200 for their phone system and they want us to set it up so that users outside the internal network can connect back to it across the web.  This system was in place before we came on board with them.  Currently what will happen is if you place a call out from the phone that is outside the network it won't get any kind of ring trills but it will ring the phone you are calling, when you pick up the phone audio cannot be heard on either end.  If you call into the direct dial number for the phone it will ring typically once and then the phone you calling it from will start emitting a loud screeching sound, and everyonce in a while you will get a busy signal.  In addition to forwarding the below ports I have also tried setting up a VPN, configuring the phone to point to the Office Serv's local IP and it would just sit there and try to reconnect over again.  I have forwarded the following ports to the phone system:

UDP: 30000-30031 (RTP)
TCP and UDP: 9000 and 9001 (SIP I think)
TCP and UDP: 6000 (this was in their old firewall config so I added it to the list)
Firewall on Both Sides: Cisco ASA 5505 (ASA 5505 at client site where the Office Serv is located replaced a firebox

So from what i can tell and from looking at the firewall logs 9000 and 9001 are getting through just fine, and the phone does register with the phone system, and I can see different lamps on the phone lighting up, which indicates that the phone can communicate with the system but for whatever reason the actual voice traffic doesn't seem  to be going through in either direction.
ctagleAsked:
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Bryant SchaperCommented:
typically, and I don't have experience with Samsung, I would say you have a routing problem, and they phone is not able to connect to the gateway or end device.  Are you running over the internet?   This would more than likely cause poor call quality, but still work.

Do the ASAs establish a VPN tunnel?
ctagleAuthor Commented:
yes its running over the internet.  i did establish a vpn and tried point the samsung phone to the local ip of the server and it wouldn't connect, i also tried doing the vpn and leaving it to connect to the external ip where the samsung server is, still nothing.
Bryant SchaperCommented:
is this sip?  I would start by doing some trace routes to the ips from each subnet, the phone probably needs to talk to the server IP and maybe a gateway IP?
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ctagleAuthor Commented:
to be honest with you  i 'm not sure how the communication works between them, i do know its sip, but I just mirrored the port forwarding from their old firebox.  i still find it odd that it won't work even across vpn, there has to be something that i'm missing but i'm not familiar enough with samsung to know what that might be.
ctagleAuthor Commented:
i've been going over all the configuration options in the phone system and i found that under virtual port configuration there is no data under sip phone informaitons but there is information under ITP, i haven't actually heard of ITP, i've tried googling but I've come up empty, does that tell us anything that could help with this?
ctagleAuthor Commented:
actually that appears to be the first three digits of the model number of the phones
ctagleAuthor Commented:
so upon further inspection i am noticing that there is no option for SIP because they have no licensing for it, according to the company owner they have never used sip before and that its a "hybrid that just establishes an ip connection".  I have never heard of such a thing, as far as i know you need somekind of trunk back to the phone system, either PRI or SIP, am I wrong in this?
Bryant SchaperCommented:
well, I would say yes, you need SIP, PRI, or Analog circuits.  But now you make we wonder if their PBX is a remote box from the provider?  I use to have a remote shelf from a Nortel that talked back to our primary switch which contained the PRIs.  SIP, but not really.

Maybe we are just missing a port or something simple.  Cisco uses a proprietary protocol called SCCP, which is SIP with additional features. I would expect Samsung to do the same.  SIP can be a bit featureless as a standard, so vendors add their own version.
ctagleAuthor Commented:
well i have managed to get call audio working one way, turns out that the ip address that i was fowarding ports to was the incorrect one (the system has three).   but I can't hear voice coming from the remote phone.  voice being sent to the remote phone goes through, but not from the remote phone.  i am also noticing that sometimes it will emit a screech when calling, and other times it won't and you can pick up the call, but the phone will never ring, only its extension light will light up indicating that its ringing
Bryant SchaperCommented:
it sounds like the phone system doesn't know how to reach the remote phone now, can you do a trace from the three IP addresses and see?

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ctagleAuthor Commented:
ok so i managed to get two way call audio going, now the only thing left is the ringing not working correctly, to fix the two way i had to foward the ports back to the 142 address instead of the 141 address that i had changed it to, it seems that my service object foward didn't work for some reason, so I changed it to individual nat rules for each of the required 35 or 36 ports and it worked.  but I still can't figure out the call ringing, i have figured out though that the first call you make to the phone it will screech at you, then if you make a call right after that again, then it will ring with out screeching but the samsung phone itself won't ring, you can however press the flashing green extension light on the phone (the line for the phone) and pick up the call.
ctagleAuthor Commented:
Well I manged to figure out all the issues.  The call audio was all port forwarding, the service object port forward wasn't working, so i built a command a did all of the rules individually and it worked, i'll have to work on that service object stuff, the ringing you were right, it didn't know what to do with the calls, sort of, after finally some what wrapping my head around the way that officeserv works i figured out that the phone i have been using for testing was never assigned any kind of DID functionality, so i found the phone number that the phone gave on caller id when calling out under the trunk configuration, found the internal number assigned to it, went to the station group, made the test extension part of an unused station group, then made that station group number the "ring plan" for the internal number assigned to the DID phone number, and it started ringing through....WHAT A MESS!! lol

thank you for your help.
Bryant SchaperCommented:
awesome, happy I could assist.
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