Is The number of VM boxes in CUE determined by license uploaded only? Or it is also related to the router type?
For example, 2811 can support 35 IP phones with CCME ver4.3, does it limited the number of VM boxes to 35 too? Since EM is available with CCME 4.2 or later, it has a need to configure more number of VM than phones.
It's driven by the license and module type NM vs AIM. Even though 2811 can only have 36 or so IP phones it could in theory have a lot more mailboxes (250) if you assign multiple extensions to phones or create general mailboxes. Refer to the Data sheet for more details: