1608's over VPN - Quality Issues

[liquidshokk]

5 x 1608 handsets at remote site connect to the head office IP500 V2 (8.1) over a Voiceflex ADSL circuit/PPTP VPN with draytek Vigor routers at each end. This circuit is completely separate to the data adsl line/router at remote site.
At the head office LAN 1 on the IPO is connected to the customer Network and WAN is connected to one of the draytek routers handling VPN to remote site and also Voiceflex SIP circuit connectivity.
Users at the remote site are configured to use the SIP circuit at head office, however they have also experienced quality issues when set to use the ISDN at head office. Users set to use SIP at head office do not experience quality issues so believe the issue may be either the adsl link (moved to 2nd provider as part of diagnostics), IPO set up or router configuration (open ports on HO Router only, strict firewall off at each end).
Have tried both G.711 and G.729 on remote site ext’s.
Remote phones have direct media path off and firewall type set to “Symmetric NAT” – Stun finds “Full Cone NAT”
Issues being experienced at remote site include speech path drop out and call disconnect. Occurs intermittently and all users at remote site have experienced issues.

Have run out of ideas!??

 

[liquidshokk]

Basic Network Diagram attached

 

[cg11]

Try running the speedtest at

http://www.speakeasy.net

at remote sites (if possible). This may give you clue if issue is bandwidth/jitter issue. Sounds like there are a lot of layers for the VoIP to transverse.....firewalls can sonmetimes kill VoIP quality too......cg22.

 

[liquidshokk]

Thanks, There aren't any firewalls between the two sites on the voice link other than the firewall functionality built into the drayteks

 

[liquidshokk]

I'm in the UK so that site won't be any good. Also the PC's at the remote site go over a different link from the voice so would mean physically connecting to the voice network onsite

 

[cg11]

What is the bandwidth on your ADSL? In USA they only give about 512k upload speeds....having said that be sure to confirm that you are using G729a codec....this can make a huge difference. I always use G729a for remote phones. Confirm that G729 is, in fact, being used in system status.

 

[cg11]

One more thing....what VPN encryption are you using?.....try 56/64 bit (DES) if you can. Encryption adds overhead too.

 

[tlpeter]

ADSL sucks for voice.
Be aware that if you use upload it also consumes download bandwidth!
You will need SDSL at least.


BAZINGA!

I'm not insane, my mother had me tested!

 

[liquidshokk]

The VPN is just set up as a PPTP connection. I tried setting it as IPSEC with a password but the two wouldn't connect (not really my area). I will double check the codecs.

The ADSL is set to Annex M which I believe gets around the upload/download issues as it evens it out. Doing that has resolved issues elsewhere in the past when using adsl for voice

 

[tlpeter]

Hmmmm, never heard of annex M but i believe you.
But still it is ADSL and probably it doesn't have QOQ on it.


BAZINGA!

I'm not insane, my mother had me tested!