Latency issue with Cisco IP phones


I’m facing latency issue (latency > 250 ms) when configuring asterisk with Cisco 7940/60 series IP phones while if I configure on zoiper with same network, it gives average latency of 150ms. Even If I ping (from server to Live IP or in reverse direction) I get latency of avg 150ms.

Attaching screenshot below

Some endpoints will prioritize OPTIONS traffic lower than other traffic, resulting it it taking longer to respond.

The only traffic I have on that ISP is of VOIP, the data traffic for that ISP is configured only on one PC which is for testing.

So do I need to apply QoS? Or how can I improve the latency?

If the Cisco is prioritizing the OPTIONS request lower, then you can’t. If others comment on whether they see similar, then that would confirm the deprioritizing of that specific traffic.

What exactly is OPTIONS traffic/request? I tried to google but couldn’t find any useful info on it

Asterisk uses OPTIONS to determine if a device is reachable and the latency. It is the latency for how long it takes a SIP request to get to a device, how long it takes to process it, and how long it takes for a response to get to us.


I configured an extension to another company having Cisco IP phones but different phone model and ISP, they are getting 170ms

Now either IP phone issue or ISP

Seems a little bit strange.

Do you have an opportunity to connect to the very same cable some other SIP-phone? Maybe even Cisco but another one.
Or the problem is with many (all) Cisco phones?
Sometimes the problem may be in RJ45 connector or in Ethernet port of SIP-phone or switch. Try all possible combinations to understand where is the point of failure.

There are about 40+ cisco phones 7940/60 with different firmware versions As you can see in the screen shot.

I do not have any other phone where I could test.

BTW is that Latency shown or registering time? and does that affect calls? because someone told me that this is phone’s registering time and it doesn’t have anything to do with latency