sundance-communications.com/forum Forums TDM Business Telephone Systems Samsung Telephones & Systems Strange Audio Problem With Three Remote SMT-i3105 VOIP Phones

Customer has a 7100 V4.82, 1 4DLM Card, 4 MGI License,Two Digital Phones, 16 3105 Phones, 3 of those are remote at another location 10 miles away. They also have (1) Polycom SIP Conference Phone at the remote location. Comcast is the provider at both sites.

The remote Polycom SIP Conference Phone Has Two Way Audio For Every Call To and From Main location no matter what type of phone calls it.

Digital Phone at main location calling remote VOIP phones OK.
Remote VOIP phones calling a digital phone at main location OK.

VOIP Phone at main location calling out to a remote VOIP phone has two way audio most of the time.

VOIP Phone at remote location calling a VOIP phone at the main location, no audio either way most of the time.

By the way, Clearfly SIP trunks work 100% of the time. No audio issues.

So it looks like everything is good on UDP 5060.

What is the issue?

Main site has a Netgear Nighthawk firewall and a Comcast Cisco DPC3939B router/firewall set in bridge mode.

Based on Samsung's recommendation, we have already replaced the MP10a and nothing really changed.

The last thing to do is to default, move up to V4.91 and reprogram by hand.

I still think it is a firewall issue of some kind.

What do you think?

MikeS in VA

how are the sites linked? VPN or is it just forwarded for phones?

If port forwarding what ports? MPS OR MGI?

General rule of thumb i forward the following and it allow me access to everything and i never have an issue

5000-5090 TCP
6000-6090 TCP
9000-9002 TCP
30000-30031 UDP
40000-40100 UDP
45000-45100 UDP

Check whitelist
confirm your Public IP is programmed in the Samsung

Cheers
Andrew

I just spent 3-4 weeks diagnosing this problem with a government contractor customer that added (3) remote Samsung VOIP phones connected to the main phone server 8 miles away.

Comcast/Cisco DPC3941B's modem/router on each end with 150 meg internet.

Customer blamed the Samsung phone system for intermittent connectivity issues.

Clearfly SIP Trunks worked fine. A remote Polycom SIP conference phone worked fine, but remote VOIP phone to local VOIP phone calls would connect 40% of the time.

Customer blamed his Netgear Nighthawk firewall/router for the problem.

I changed the entire phone system out with a smaller test unit--we had the same connectivity problem.

Customer changed out his Netgear Nighthawk firewall/router for a basic Linksys/Cisco unit--he had the same connectivity problem.

Comcast came out and changed the DPC3941B 's with the older style SMC boxes and all troubles went away.

I could find only one thread on the internet that probably explained the issue. The DPC3941B's apparently have a SIP ALG setting that cannot be turned off.

SIP ALG settings will most of time mess with VOIP calls whether it is proprietary VOIP phones, basic SIP phones or SIP trunk phone lines.

MikeS In VA