I don't know if you have a specific subnets permitted in the CUPS ACL
This is dangerous and incorrect guidence. The Incoming ACL allows the addresses defined to bypass authentication. In other words, I could impersonate your CEO if I wanted to. There are only two common use cases where doing this is appropriate: 1) the CUxAC server IP; or 2) older versions of CCX where CAD didn't support DIGEST authentication.
As for the original question: your English is difficult to understand. Is the following problem statement accurate?
When 5412 on CM2 leaves a voicemail for 5411 on CM2, the MWI is lit for 5411 but Jabber does not reflect the waiting message?
If this is accurate, is the message also shown in the Web Inbox? https:///inbox
The serverIP should be the CUC server defined in the voicemail profile on CUPS for the user who owns 5411.
Ok, assuming that is the same IP address shown under Help > Server Status/Health in Jabber then you'll need to pull logs to figure this out. The question will be why doesn't the Jabber client get notified of the new message; depending on the version this is either over IMAP IDLE or HTTP but the log is the same.
These are the paths to get to each CCX logs through CLI. They may be helpful if you are having issues accessing RTMT or downloading logs through it.
If you want to download them you have to prefix "file get " and you can add one of the options (re...