atcomsystems.ca/forum Forums TDM Business Telephone Systems Samsung Telephones & Systems Bizarre Post Dial Hum

Hello All,

I have a OS7400 that has a line hooked to an 8SLI card.

The line is then connected to a fire monitoring system as a backup phone line. This has worked for months.

Recently, in the middle of the night the fire monitoring company has been issuing a warning that the backup line has no dial tone. I went on site and checked and it does in fact have a dial tone. But it is exhibiting a weird condition. If I hook a phone to the port on the 8SLI I get dial tone, I dial, then I get 2 to 4 seconds of hum, then silence, then ringing. I think the monitoring company is determining the hum as a no outbound condition.

The hum sounds like machines, or an AC compressor, like if someone turned up a microphone in an empty room. It goes away after a couple seconds, then the call rings and gets connected.

Any idea what I should be looking for? It is not happening on any of the other "Lines" hooked to the 8SLI just this one.

Thank you in advance.

Disconnect line from alarm system and check with butt in at Demarc.

I thought it might be the line or the alarm system causing it. I plugged direct into the port on the 8SLI and still get a long delay and hum after completing my dial. This goes away at 2 seconds, then I get ringing. It has to be something either in the Officeserv, the firewall, or the SIP provider.

I don't have a butt to check with (that sounds weird).

I get dial tone immediately, I dial, then get hum, silence, then ringing.

Then you need to get one .... or hire someone that has one. You need to determine if the issue is with the line itself.

I hooked a butt test to the SLI port on the OS7400. Still get the dial tone then hum after dialing. Because its SIP, what is the procedure for going deeper into that line than the front of the SLI card?

I checked all of the ports on that particular SLI card and they all do it. I have another set of SLI cards installed (for different sub-company) that it doesn't happen on, they all hook to the same SIP provider, same OS7400 cabinet, same internet connection, and get passed through the same firewall. I am starting to think that SLI8 card might have gotten whacked/damaged.

Maybe worth testing the ports on an internal call, this way your not using the SIP trunk.

Dialing 0, and intercom calls all work flawlessly. When I pick up a phone and dial zero it rings so quickly it would be difficult to hear any hum, the instant I hit the button its ringing.

Perhaps part of my problem is the time it takes to make an outbound call. I just timed the call from final digit dialed to ring at 8 seconds. Just seems long.

The delay easy to fix.
Just edit the digit length in the lcr tables to be the correct length for the type of number dialed then append a #.

Your initial post didn't mention SIP trunks so my suggestion to test with a buttset was pointless.

I don't do Samsung so i don't know if different extensions have different entries in the LCR tables but if extensions on other analog cards are using the same SIP trunks without an issue that basically eliminates the SIP trunks as the issue.