Delay on SIP trunks

[Hershel]

Setup:
5000 HX ver 6.1
24 IP phones
6 SIP trunks (babytel)

Dedicated cable drops to a TP-Link POE switch
Cisco RV042 router connected to a cable modem,
Internet Stats (real world)
  - 2.6 up & 23 down
  - Latency 80-90ms average
  - Jitter 3-4ms

Callers are frequently experiencing a lag or delay on outside calls.  The quality of the voice is fine, it just seems to take 1-2 seconds to get to outside party.   This obviously creates some awkward pauses and doesn't  I have observed this first hand several times while onsite. 

The delay / lag is noticeably increased when calling another customer who is using SIP trunking, although through a different carrier.   

Working through regular channels with babytel and Mitel but figured I would see if there were any suggestions.

[Tech Electronics]

Hershel,

Well the two obvious things you can look at, which I am sure that Mitel has already, is your Audio Frames/IP Packet and your Minimum Playback Time.

The higher each one is the greater the latency, but the more jitter is reduced. To find these look under your SIP trunk programming for the Call Configuration it uses and see what they are set at. If they are default then most likely that is not your issue.

Another thing to look at is whether or not their equipment is doing deep packet or SIP inspections as those will slow down the entire traffic into and possibly out of the network.

Get a wireshark capture when this is going on and you will see how long the turn around is on your side. Unfortunately you won't be able to see what is happening on the other side unless that company is willing to work with you and provide those.

Thanks,

TE

[Hershel]

Audio Frame/IP Packet = 2
Min Playback Time = 20

Mitel also had me change things from G729 to G711u, this seems backwards when trying to address lag/delay. 
Thinking about changing that back

[Tech Electronics]

Hershel,

Unless you are having problems with it being G.711 I would leave it at that. They were probably thinking that the compressed audio when losing packets made it seem as though there was some latency.

Thanks,

TE