SV8100 SIP Phones over VPN

[thewebweazel]

We have a remote SIP Phones (SP310 and DT700) that are connected to our SV8100 via VPN (IPsec)connection. When this phone dials externally (connection to the Central Office is a Basic Rate), the external side complains that the speach is breaking up. When speaking to internal extns, which are also SIP phones (DT 700) both sides have clear speech. I have replaced the IPLA card but the problem still persists

Does anyone have any Ideas where the problem may lie, I have spoken to NEC Helpdesk and they acknowledge that they have come across the problem in the past and believe that the fault lies with the ISP. I cannot comprehend that this is the case as internal calls across the VPN between SIP phones are OK

 

[eddiebullman]

what bandwith do you have on the VPN as i have had a set up like this running with no problems
we used two draytek routers with a LAN to LAN vpn.
also you could try changing the codec

 

[loebjack]

We use a similare setup for a chain of retail stores. It seems to me that it is a issue with voice traffic bound to the SV8100 over the VPN. After the initial call is started, the DT700 IP phones will start a Peer-to-Peer call for internal calls, and bypass the SV8100. You can test to see if this is phone to SV8100 issue over the VPN, by disabling Peer-to-Peer (program 10-26-04 - DT700 Peer to Peer). Then all DT700 will act the same for internal calls as they would for external calls. If internal call quality degrades, reenable Peer-to-Peer and look at your routing from the VPN to the SV8100. It could be that some of the data is being delayed by a packet inspection of VPN traffic to your server network. It all depends on the network topography.