I do need help.
If have a Cisco Router 881 with configured ipsec VPN to a central router. When I connect a phone (without any QoS) I can Log on (on the phone) and I can set up a call. The call establish and I can talk about 5 minutes. After this time range (4-6 minutes) I get a termination of my voip connection. My data connection is tested by a ping through the vpn tunnel and it works without any failure.
Some help will be appreciated.
now I see this is a newer router and so the new licensing aspects apply sorry for my basic note.
About QoS for VoIP:
I would change the configuration to have not a simple IPSec tunnel but a point to point GRE tunnel that is protected by IPSec.
This gives a tunnel interface object where:
you can run a routing protocol of choice to connect central site, this is helpful for troubleshooting
and/OR you can apply QoS.
you can control how your traffic is sent to the internet and you have limited control on what you receive on branch.
But the same is true for central site.
you need to know what are the available bit rates in direction branch to central office and central office to branch.
if it is supported and it should be, a hierarchical two levels Qos is good:
a parent policy that shapes all traffic to a rate <= effective rate in outbound direction
a child policy invoked by parent policy that implements a scheduler with a priority queue (low latency queue) for VOIP RTP bearer channel and some other normal queues for data traffic. VOIP signalling traffic can have its own class or it can be classified and put into priority queue.
You need also to calculate based on codec in use (G.729 probably that takes 24 kbps per conversation considering only IP overheads) how many conversations can be allowed at the same time. This is call admission control and it is very important to achieve good quality.
This needs to be configured on IP PABX controlling phones.
Hope to help