UCM62xx FXO delay times versus UCM61xx


I have a UCM6102 using only one FXO port for outgoing/incoming calls. Since I started using it a year ago, the FXO delays have been terrible. I have followed suggestions posted here in the forums which help some but still the delay is really unacceptable to me. Conversations are constantly difficult, especially if the other caller is on a cell phone. An analog phone has NO problem on the same physical line. I just think it’s a limitation of the UCM61xx and will never be any better, even with firmware updates. BUT I’m hoping the UCM62xx, with the faster processor, has notably better FXO delay times. Does anyone have experience with this on the UCM62xx?


It is caller id, analogue line sent it late usually. 1-2 signal.
CPU does not matter.
If you turn it off then it should proceed faster.



I think the issue is the latency in the audio making it problematic for each user to use effectively without talking over one another. I too have observed it to varying degrees on different installs, but while noticeable, it has been tolerable. I have an analog line simulator and did testing, but using that, I was never able to recreate the issue. However, I have made the casual observation that it seems to be more noticeable when the telephone service is provided by cable companies thru eMTAs.

One thing you might try is to install a duplex coupler on the FXO line input to the UCM. Then make/take calls where the delay is evident. While in a call with the latency, you should be able to take a butt-set, if you have one, or an analog phone and tap into the call and then listen to the call to confirm if the delay is only thru the UCM (butt-phone=good, extension=bad) or somehow being impacted by the UCM being in the path so that even the audio coming into/out-of the UCM is affected (butt phone=bad, extension=bad). While this won’t solve the problem, it will at least confirm at what point the delay is being introduced.

Other than the above, the only thing I can suggest is to try the latest firmware and failing that a ticket to support.


Yeah my mistake, i should read more.
Mobile is less and less reliable due to heave traffic on antenna. This generate delays.
It can be UCM fault, bur when we have good to PSTN and bad mobile then i really doubt.


Have you tried the ACIM Detection? Go to PBX – Ports Config – Analog Hardware. Then click the Options (pencil) of the FXO Ports and click on Detect. The system may change the impedance value for the line.



ACIM will most likely not give any relief as this is for AC IMpedance settings. ACIM has more to do with the connection aspect of the PSTN line and the energy that it can handle given the loop length to the CO. It can fundamentally cause a mismatch which will usually result in echo or, on the opposite end of he spectrum, low gain, but will not impact the speed with which it is delivered or sent at the analog level.

It is certainly important to run the diagnostic so that you know the UCM is properly matched to the PSTN line, but alas I do not think this will solve the latency issue.

Your best bet is open a ticket with GS and see if they can help.


I’m looking at a 6204 and would need properly functioning FXO ports.

Has anybody using a 62xx series noticed voice latency when using the FXO ports?


I’m using UCM6204 and i can’t receive incoming call, it ringing and i saw the incoming call as well on the status trunks.

the only thing working as of the moment my outbound call & internal which is the extensions.(1000 - 1005)

I urgently need help here. :frowning:

My device are UCM6204 and GXP1620.


You should start a new thread as the issue you have is not the same as the post indicates.

The description of the issue is somewhat lacking and the snippet does not really tell us much, You indicate that you can’t receive incoming calls and then you indicate ringing which is confirmed by the status lights.

Does ringing imply that the phones physically ring or that is merely the indication from the UCM lights?
How long has the system been installed and is this a new issue related to the installation or is a new issue that just cropped up on an older install?

Reboot the system and then when back on-line run the various port tests and insure that the settings for the FXO ports are correct for your locale. You can find the tests in the manual. PSTN lines can change, and it could be that the line is no longer optimized for the current conditions.

What I have suggested is pretty generic for any FXO situation, but there was not really enough detail to understand the precise issue faced.


ive started my own separate post.


the delay in your case is not due to the power of the cpu or memory occupation, so switching to 6202 does not solve the problem, keep in mind however that the 61xx series is out of production.
There are some tests to be done on the analog line to adjust the tones, impedance, etc. …
1 - press the “detect” button inside the “Analog Trunks” -> I recommend the semiautomatic
2 - Interface Settings/FXO Ports -> detect (obviously in Interface Settings all parameters must be corrected)

after each test restarts UCM, IF YOU DO ALL Correctly WHERE YOU HAVE AT LEAST OF THE BEST,
in case FX01 could be faulty/defective to use FXO2