I am unfamiliar with the Alarm Relay IP/CDMA or combo IP / cellular communicator box that you are using; if that is what you are using today as a primary CS monitoring mechanism.
There is a web page on the Alarm Relay site that speaks to 2G versus 3G/4G alarm monitoring here...
2G vs. 3G/4G: What Changes Are Coming in Alarm Monitoring Technology?
What is the MFG and model number of the digital communicator you are using?
Is it this one from IP Datatel?
Doing a search here saw one OmniPro user thinking of using Alarm Relay and one of these boxes but not sure if that specific user went to using the box.
Ideally if you could test using a copper line or maybe a VOIP line you could check on your OmniPro 2 panel stuff.
Personally I would believe its more an issue of your digital communicator programming than the OmniPro panel stuff. It is a simple connection from the OmniPro panel to the combo IP/cellular backup device.
Best to have a granular look with PCA at the DCM settings.
Yeah many folks here on the forum had a few issues with the update to V.313 as there were some major changes there.
Your DCM settings could be trashed maybe. The settings are basic and easily changed via PCA.
Did you first notice the issues after you updated the firmware?
Leviton in their rush to implement the Omnitouch 7 / email board stuff overwrote some of the basics in the base old firmware.
This may or may not be an issue relating to your concern.
Not sure if this will help but give it a try as I ended up doing this (along with some other Cocoontech folks here using the OmniPro 2 panel).
1 - back up your settings
2 - cold boot your panel
3 - configure the IP access or use serial access and PCA.
4 - using PCA upload your current configuration
If this doesn't work then it could be your alarm relay digital communicator or your panel might have a hardware issue where you have to have it repaired.