Phone services bouncing in Cisco Jabber 

Strange behavior, right 😀
You might face this issue one day like what I saw today
Customer called and said :
“Eslam, I can’t use my Cisco Jabber to make phone calls either in the office or outside”

I asked him to describe the issue in detail for me

And he said
“My soft phone service only shows healthy connected state despite the service appearing to bounce in the main Jabber client window itself. It will after several hours (can’t be sure exactly how long as it varies) then show a constant connection in the main window allowing the phone service to function correctly.
To be clear until it shows a constant connect in the Jabber app itself I’m unable to use the Soft phone service.”

This mean, sometimes Cisco Jabber is registered and working fine and sometimes can’t register, but why?

I asked him, if it was working before or never worked before and he said yes it was working normally , and I joined him in a WebEx Session to check the issue , and once he joined I saw the Cisco Jabber connected and appear in front of me registered on CUCM Page ,for the first time ,  I couldn’t understand this strange behavior as he described and why it could happen and to be honest

I told him that, this properly will be due to network or connectivity issue

But after 30 minutes he called me again and said the issue happening again

I asked him to send to me the Report for Cisco Jabber, by the way he was using Cisco Jabber for Mac OS

Below GIF shown how its look like on the app itself

First, I tried to Check his account setting, CSF Device, association, everything looks good

Then Moved to check SRV records, to make sure the server can reach Call Manager Servers to register with, and also it was configured correctly

Next, I tried to look at Cisco Jabber Error report and I saw weird behavior

As you can see in the below image, I took the Cisco Jabber log inside Translator X, and I saw this

When Device request to register to CUCM Sub1, server refer it to register to Sub 2,
and when the device try to contact CUCM Sub2 as instructed, Sub 2 will refer it to Sub 1

And Cisco Jabber stay back and forth between Both CUCM Servers without successful registration

But why ??, why it’s can’t register now, and other times it can register normally what changed!!

Actually, it tried to check the log file searching for any error message in the SIP registration request and reply and guess what :D,

I found this little message

I think now, you know the reason behind this weird registration

Both Servers fully capacity now, Maximum Number of Phone that each server can handle is already registered right now ,, CUCM reject the registration request because he reached his maximum capacity

My advice for you, If you going to learn something from this case

Don’t trust any Unified Communication Design engineer, because if your UC system design is not followed by Cisco Best Practice you will face a lot of unnecessary  problems, but in the same time it will be good change to learn