Audio Delay On Outbound Calls


I am having an issue where the first 5-10 seconds of a call (not every call), the caller hears silence and then all of a sudden the audio kicks in. I have recorded the calls and it is the same on the recorded call. We have the HT818 hooked up to an NEC phone system and they were getting some sip vicious activity and I allowed called origin to only come from our proxy server. That really is the only setting that we changed.


try changing codecs, put only PCMU/PCMA on both server and HT818 side


Just so it is clear - you have a Sip Provider --> Internet Connection --> Router/Firewall --> HT8xx --> Analogue FXO ports of the NEC.

Delay is happening some times - is it when there are a few calls already established with another coming in or is it at random?

Do you have SIP ports open to the world or just the SIP provider?



Yes Sip Provider – Internet Connection --> Router/Firewall – HT8xx – Analogue FXS ports of the NEC.
On the HT818 they are FXS ports, to FXO ports on the NEC.
They aren’t receiving a ton of calls at all and the delay is outbound only. Only one call at a time. We don’t have any ports open at all, everything is behind the firewall.
I have installed these many times with no issue and just can’t figure out why this one is giving me such a pain.
Thank you for your help.


what has changed in your deployments ? firmware? router?


You indicated no ports open at all, so how do inbound calls arrive at the HT? Do you have keep alives enabled? However, you did indicate that you allowed “called origin to only come from our proxy server”, so am a little confused about this.

Please read the following as it is essentially the same, but as you have a 818, you will need to expand the local SIP port forwarding and perhaps the local RTP ports as well at the router.