Cisco Support Community
Community Member

2 seconds delay on SRP527w FXS port...

Hi there,

I could use some help, advice or just lend me an ear on this one; I have a wierd "2 second delay" issue with audio generation on a SRP527w.

When in a call, with myself on both ends of the setup

DECTphone - FXSport on SRP527w - VOIPprovider <> PSTN/GSM - Mobile

I can hear my voice on the mobile immediately, as expected. However, the same words i speak (having both the DECT and the Mobile at my ears), are heared on the DECT with 2 seconds delay. Trust me when I say that this is the base for a poor rated telephone call and misunderstandings therein.

This issue is the same when calling to other mobiles and even land-lines, both in being called and being the calling party... Every time the voice from the other side is heard "delayed" on the DECT.

Testing the DECT on a normal non-voip connection results in a normal conversation, as far as this is possible with me talking to myself

I do have a separate CBR pvc for the voice on the SRP and to investigate the issue I've put the SIP user on a soft client, using a UBR pvc on the same SRP, both pvc's do use the same provider but diverend gateways. And with the UBR + softphone i do not have this "2sec delay" issue.

So, ruffly said this seems to locate the issue in the SIP>FXS DSP, with specific only the digital>analog decoding/generation (not with the analog>digital encoding, as i hear myself normally on the mobile, with no/normal msecs delay).

Does anyone recognize this issue? Anybody with the same experience on SRP527w + FXS port?

(Firmware is the .24, is there a "best" known oldy?)



Message was edited by: TS ( O -> S, as in the right port ;) )

Everyone's tags (3)
Cisco Employee

2 seconds delay on SRP527w FXO port...

Hi Michel,

In your configuration, could you please check that you have the following settings in place for the FXS port you are using:

Network Jitter Level: High

Jitter Buffer Adjustment: Up and Down

Then, when you are in a call, please go to the device GUI and take a look at the Voice > Info page.  What values are you seeing for Decode Latency, Jitter, Round Trip Delay?  Are you seeing any losses or errors?


Community Member

2 seconds delay on SRP527w FXS port...

Hi Andy,

Thanks for the ideas and settings.

I tried Network jitter Low, High & Extremely high before, no change in audio delay.

For the test just below, it was set on High, Jitter Buffer Adj was already on Up and Down.

Output: (1:15 min call)

Call 1 Decode Latency:        80 ms         

Call 1 Jitter:        4 ms  

Call 1 Round Trip Delay:        Not Available

Call 1 Packets Lost:        133 

Call 1 Packet Error:        0

So, pretty good values.

I tested port 2, never changed a setting from default there (except SIP user and such )

Same delay: when speaking into both the mic's, i hear myslef rightaway on the mobile phone, and 2 secs later on the DECT.

Values: (15 sec call)

Call 1 Decode Latency:        50 ms  

Call 1 Jitter:        1 ms  

Call 1 Round Trip Delay:        Not Available 

Call 1 Packets Lost:        37 

Call 1 Packet Error:        0

Same good values, i guess...

Other things i can/should adjust?


Cisco Employee

2 seconds delay on SRP527w FXS port...

Thanks Michel,

This doesn't seem normal.  Could you provide some more detail regarding your WAN interface configuration please?

Better still, could you provide a copy of your configuration please? (You can use private community mail if you prefer not to share publically).

Grab the config by logging in to the SRP, then paste the following to your browser address bar:

On the resulting page, right click and view source, then save that file and send to me.

Many thanks


Community Member

2 seconds delay on SRP527w FXS port...


Thanks for helping out; the issue is fixed.

The codec used was G711 family and my provider expected G729. Bandwidth was the issue, causing the SRP527 to wait for the dropped packets to arrive (which they didn't ). This leads to 2 seconds delay (of buffering), after which the SRP decided to play the audio.



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