SCN Echo problem

[liquidshokk]

Hi All

We have a customer that has 5 sites using SCN. All sites are IP406 except one with IP403 (Annoyingly, as cannot upgrade to latest version) The central site has a 406 with a VCM30 card in it.

All boxes are on 3.2 (61)

Only two of the remote sites were setup for external calls to go out through the central site (currently planning the same for the rest) however one of them is experiencing bad echo on outgoing calls. We have swapped the VCM Card at the affected site then returned and swapped out the 406.

I am startting to believe it is the VCM card at the central site that is the issue, however I do not know enough about the causes of echo to say for sure. Could someone advise?

Also eventually with all remote sites going out through the central site, is this going to cause extreme overloading and cause further problems? or has anyone got a similar working setup? the number of users at each site varies from approx 6 to 60

Many Thanks

 

[tlpeter]

If it is only one site then it is not a vcm issue
Is there any QOS on the line ?

ACA - Implement IP Office
ACS - Implement IP Office
ACA - Voice Services Management
______________
Women and cats can do as they please and men and dogs should relax and get used to the idea!

 

[liquidshokk]

I have just received confirmation that since configuring another site to go through the central site it too is now experiencing echo on external calls.

We dont look after the lines between the sites but they are mpls lines using cisco routers which we are assured have QOS setup. there are separate lines for voice and data.

 

[tlpeter]

Within a SCN Every site goes true the central site !!!
There is no other option for a good working SCN

What are the ping times ?
If you have an 5610 or 20/21 then make a call to the central site and press the options button
Then you get an option for call quality
I like to know that results

I still think it is not the vcm but a network problem

ACA - Implement IP Office
ACS - Implement IP Office
ACA - Voice Services Management
______________
Women and cats can do as they please and men and dogs should relax and get used to the idea!

 

[liquidshokk]

Previously we have only had internal calls going across the link to the central site and incoming and external calls going out over the remote sites individual Analogue trunks. The problems have started since sending all calls through the central site. (The original SCN setup is surely ok if the sites have their own lines isnt it?)

They are using analogue handsets on all sites apart from one of the sites (which ive just realised has a small office not a 406) and that site has 5402's..so unable to check the call quality option you mentioned.

We have checked the switch ports that the ip offices are connected to and they have minimal traffic reported with no errors.

I am about to ping from the switch at one of the affected sites to the phone system at the central site and will post results.

Thanks

 

[tlpeter]

What i mean with the lines in a scn is that the remote sites only need an ipline to the cetral site
Only the central site has multiple iplines (to the remote locations)

What codec is set on the iplines ?


ACA - Implement IP Office
ACS - Implement IP Office
ACA - Voice Services Management
______________
Women and cats can do as they please and men and dogs should relax and get used to the idea!

 

[liquidshokk]

oh i see, sorry

Yes all the remote sites have only one IP line ;-) I just meant they also have trunks for external calls

At the central site some of the ip lines are g.711 and some g.729 oddly. One of the affected sites is g.711 at the central and remote end

 

[tlpeter]

Try it with G729

It uses less bandwith then G711
Maybe you do not have enough bandwith
Use the same codec for every site


ACA - Implement IP Office
ACS - Implement IP Office
ACA - Voice Services Management
______________
Women and cats can do as they please and men and dogs should relax and get used to the idea!

 

[kflounders]

What are they dialing out from once they get to the main site. Is it PRI or Analog?

 

[liquidshokk]

Ive had it confirmed that we have tried changing the codecs to g.729 but only on the affected sites which made no difference. I am arranging to put all of the sites to g.711 as im told that echo isnt caused by lack of bandwidth and that having a bigger packet size can prevent problems such as echo (how true is this???)

At the central site the calls are going out of two PRI cards on the 406. outgoing calls on the central site are set by shortcode to go out over line number 1 which is one of the pri cards. the other pri card is line number 5, should these be the same?? Not sure if this is relevant at all however.

 

[ronromano]

Are you using pots lines?

http://www.nu-tel.com

 

[liquidshokk]

calls were previously going out over analogue trunks at the remote sites as mentioned above but the problem has started since going across the IP MPLS lines to the central site then out of the PRI there.

Thanks

 

[spridge]

MPLS Circuits

What type of circuit(s) are being used for the MPLS links

Lease Line
DSL
Ethernet
?

 

[liquidshokk]

It is a managed service using cisco routers going into a providers MPLS cloud

 

[kflounders]

Who is the provider?
Check that both your voice and signaling Diff Serve settings are correct.
Can you connect a system directly to the main site as a test to place the blame squarly on the WAN?

 

[liquidshokk]

Not sure exactly who the MPLS cloud provider is as looked after by a reseller.

The diff serv settings are set correctly for the settings shown in the ip office configuration (default i believe) Again this is dealt with by the managed services company.

Unfortunately due to the size of the customer (6 sites, approx 400 customers) we arent going to be able to do the mentioned test at the central site.

Currently 2 remote sites of the 6 sites are experiencing echo which only happens on calls transferred from or going through the central site.

Codecs on all sites and lines being set to G.711 tonight

 

[kwing112000]

I generally use 729A on MPLS. 711 on the LAN and 729 on the WAN. Thats what our data group has always suggested. Also do you have direct media path on or off? that could be it. it should usually be on for MPLS.

Kevin Wing
ACA- Implement IP Office
Carousel Industries

 

[liquidshokk]

direct media path is set on some and not on others. one site affected has it ticked at both ends and the other doesnt so cannot pin point it to that.

I want to get the direct media path set to ticked on all sites eventually to lessen the load on the central site but i need to make sure with the managed services company that there are direct links between the remote sites right?

Thanks

 

[kwing112000]

i would turn it on at all sites and see if it works. that could be your issue right there. I have found it is almost always either on or off on everything. with it on the call will use the main site for call set up and then let the 2 remotes talk directly. with it off the main has all the call control.

Kevin Wing
ACA- Implement IP Office
Carousel Industries

 

[liquidshokk]

does there not need to be a direct line between the two remote sites though once the central site drops the call setup or does traffic continue to run through the central site?