VOIP Troubleshooting tips

VoIP is an integral part of most companies. Some have true SIP Trunks and others use various communication protocols such as RTP or certain UDP ports.


Gather Data

There are several tests that can be run to gather jitter, latency, etc. 



Refresh SIP sessions:

Once you go online with OmniShield, rebooting your phones may help them reestablish their SIP sessions with external server.


WAN IP Whitelisting:

WAN IP whitelisting may be required by your VOIP provider as well. Your WAN IP when connected to the Cloud Link would be as shown in your portal.  Use a "whats my IP" online tool to verify you're on OmniNet and that it corresponds as listed in the portal.  Give this IP to the VOIP provider for Whitelisting.


DNS Servers:

Static IP configuration on VOIP phones can sometimes cause issues. Make sure the phones have non-ISP provided DNS servers assigned as some ISP vendors block DNS requests originating from other networks (In this case OmniWan network). If you are running your own DHCP server, please check what DNS server is being assigned to your phones.


Gateway settings:

If you set your OmniShield network to match the existing network, then your gateway should change that you don't have to worry about network gateway updating on static VOIP phones or your DHCP server (if running your own). If you didn't customize your OmniShield Cloud Link to match the pre-existing network, then please be sure to update static devices and/or any internal DHCP server to use the new settings.


Security Bypass: 

Optionally, the portal has a feature to add trusted destinations by IP or URL so that our security engines leave this outbound traffic alone. Sometimes this does the trick.


Topology bypass: 

Some partners will choose to route VOIP traffic around the OmniShield network and send it directly out to through the modem. This is typically easier if VLAN capable switching is in place OR if dedicated network voice switch and physical network drops (not shared with PCs) are run to each phone.


Further analysis:

Example source VOIP Phone IP. If you provide an IP address for one of the VOIP phones, OmniNet support can review the logs to see if we can find any signs of issues with that device.  Provide the source IP of a device and time the problem was reproduced on.

Third-Party resources

Vonage Support

Vonage Support - Sound Quality Issue


Have more questions? Submit a request