I got some strange error in POM campaign manger as below. We have 400 POM Licenses (outbound ports) for callback calls and 200 MPP ports. This means maximum of 200 calls can be made concurrently.
But when the number of callback calls reached approximately 100, then those calls goes to queue and cleared after sometime.
FYI - We updated new license file (with 400) yesterday in Session manager. Before it was 78 only.
My doubt here is, new license may not be taken. Is restart required for session manager ? or any other points need to be verified?

I'd like to help but you didn't provide enough context and some of your information is a bit confusing. What type of POM licenses do you have 400 of - automated voice, preview agent, or predictive agent? Those licenses each come with a set of Experience Portal (EP) ports that will need to be administered on your EP and allocated to your MPPs. Obviously, your SM must be configured to allow each of those EP ports to make and receive SIP calls. For example, if you have 400 automated voice POM licenses, you would have received licenses for 400 EP ports. Four hundred preview licenses would have given you 800 EP ports (one outdial and one nailup) and 400 predictive licenses would have given you 1200 EP ports (3 outdial and one nailup). Depending on what type of POM licenses and campaign you are running, those are the ports you need and should have licenses for. Obviously, the SM must be licensed/configured for that number of ports. I don't know enough about the SM to tell you whether it automatically picks up a new license allocation or whether some action (possibly restart) is needed to enable these new licenses.