sundance-communications.com/forum Forums TDM Business Telephone Systems Mitel Telephones & Systems SX-200 Digital Dropping inbound calls

My next step would be to put my buttset on each port off the adtran, before the PBX, then call till you hit that channel. If you can make it happen while connected to your buttset, you can prove that the PBX has nothing to do with the problem.

Telco's & CLECs usually don't take you seriously until you prove that it's not your problem.

Good idea, Telephoneguy. I was considering busying out one trunk at a time at the punchdown to see if the problem disappears. May try again with the buttset. Wish the problem was more than 4-5 times/day.

Thank you,

-=Mike

Intermittent problems always take forever to troubleshoot, and the customer usually thinks that you're padding your time -- but the fact is, if it ain't happening, you can't trace it.

I own a Mitel SX 200 phone system 9110 Series. Serial number BA 30125. It is cream color and is about 3 ft high by 2 feet wide, sits on the ground. It has been a work horse for our hotel for over 20 years.

Recently, we began experiencing dropped calls. Callers call in and when the call hits the phone system, the call will simply drop off it never connects. Caller calls back and eventually gets thru. Another symptom we are having is that of an ‘echo/Europe’ effect where it sounds like a call 50 miles away is overseas with an echo or a delay.

We get our calls into the hotel thru fiber DS 1 that goes to an Adtran Channel bank then to my Mitel. This has been the same set up since 2005 when we moved from copper to fiber.

Yesterday, calls were dropping at such a rapid rate that I deciced to simply power down the mitel for 1 minute and power back on. This temporarly corrected the symptoms for the better part of the day. However eventually by the next day the symptoms re-appeared.

By this morning we were getting at least 10 dropped calls each hour again. So I thought to try to turn the Mitel control box off. I did that one hour ago and we stopped getting dropped calls as of this writing.

I contacted the company who installed this unit (yes they are still open) and the tech that has worked on it for years, after initially telling me that I would be throwing good money at bad and that I needed to budget for a new phone system, indicated he thought the 217 processor might be going out.

In the 3/11/05 post telephoneguy suggests looking at the Adtran box for what appears to ba a similar issue, would you still suggest that five years later? Or based on my post specifics would you have other suggestions?

Jordan Brown
[email protected]
509 679 1123

I'm afraid I have to agree with your technician. The 217 was discontinued in the late '80's. You have gotten your monies worth out of that system. Heck, you'll probably see a significant drop in your power bill when you upgrade to an ICP. And the phone room will be a LOT cooler. But when he says that your present system has no significant trade-in value, don't be surprised.

I'm going to step in and politely request that such a question begin as a new topic rather than tacking onto a years-old thread. Since this topic has been continued, I suppose that it is too late. It would be most-constructive to try to assist further at this point.

Jordan, we often have a difficult time in assisting when posters identify their location with entries such as "Enzian Inn". Telephone companies throughout the country (or world for that matter) have varying standards of service. Please change your location information in order to afford us the opportunity to have some clue as to where you are located (geographically). We don't steal identities here; we only need this information to reflect upon potential similar instances that we may have encountered in your area. Help us to help you.

Frankly, I am surprised that your system has managed to function properly as long as you say that it has while connected behind this Adtran unit. The Mitel SX200 was a REAL PBX that relied upon precise line voltages, proper polarity, loop current and supervision from the central office. Mitel systems are notoriously intolerant of line voltage that is out of range from the industry-standard 48 volts DC when on-hook.

Most of today's channel banks, pair gain, CATV modems, IADs, etc. only provide line voltages in the 34 volt range. Again, I can't believe that you've managed to get along as long as you have under such a scenario.

There is nothing wrong with your SX200. The line voltage being delivered by the Adtran unit is not sufficient for the system to understand that a legitimate call is present. Incoming ringing voltage is enough to 'shock' the trunk port into thinking that the line voltage is sufficient, but after it is answered, the system soon realizes that the voltage is below industry-standard thresholds and drops the call. That is what it was designed to do.

You can revert to real trunks from your local telco that must meet certain guidelines for voltage, current, etc., assuming that you are in the United States or Canada. This will certainly solve your problem if this is the case.

You can also refer this matter to your dial tone provider and mandate that they are providing +/- 48 volts on your trunks. I'm sure that they aren't. I'm equally sure that when/if they do, your problems will go away.

Yes, 217 is very old, but it is solid as a rock when it is fed what it was designed to expect. Granted, the newer systems have been designed to be more tolerant of deviation from industry standard line parameters, but why should the end user have to replace their hardware because their service provider isn't following standards? Something to think about.

Sorry for the rant, but in this case, I think that you are well-within your rights to demand that the line parameters be within specifications. They aren't.

Thank you so much for the thoughtful reply. I did change my profile as suggested. In the other forum I participate in it is encouraged to search first your specifc problem and try to learn from what has allready been covered. I thought I was doing a constructive thing by tieing this post to a similar problem. For future posts, I will begin new.

As I prepar to communicate with my service provider can you help me with the following questions?

1. I have my staff document every drop call coming in. Prior to the shut down of the Mitel box we really were getting at least 10 drops an hour. When the unit was shut down, they occurred at a rate of four (4) drops per six to seven hour period. Is that just a fluke? Or when i power down the Mitel does the Adtran also reset?

2. I made the change from copper line to fiber nearly five years ago. I am sure my provider will say back to me that if this was a them problem, it would have surfaced before then. Can you think of changes on their end that would have recently caused this to begin? Are their common upgrades with T1? Could their be software upgrades necessary with the Adrtan ?

3. lastly, how difficult of a process is it for them to verify that they are providing +/- 48 volts to the trunks? Or said another way, is asking them to come check and correct a simple thing for them or would they be looking at large expenses?

Thanks in advance for your insights.

Wow, a blast from the past.

First, It's good that you're logging the problem. This will help the tech when he goes through the logs looking for the issue. When you power down the Mitel, the T-1 will drop on your side first, so the Adtran should show Red alarm (problem your end) followed by a Yellow alarm (problem their end while the T-1 syncs the clock) followed by an all-clear.

As for the second question, how does the fiber convert to T-1? Is there, for example, a "channel-bank" at your end? If so, then you can go down through the channel-bank interfaces on the copper side, and verify dial-tone and voltages.

As for what the telco will charge you, well, that's up to them. If you have a local Mitel vendor whom you can use to buffer the process for you, that would be preferable.

And, with due deference to those who correctly point out that a well-maintained SX-100D is nigh-on bullet-proof, I would also mention that this is probably a 30+ year-old system, and that it backs up on 5 1/4" floppy disks. I pointed this out to the OP in 2005, and that was 6 years ago.

You've gotten your money's worth from it. Plan in the next three or four years to accrue Capital Expenses for a replacement -- You'll enjoy the improved features of the SX200 ICP.