CUCM 8.6.2 DHCP class B subnet mask problem

[Marc El Achkar]

Hello,

I have a a CUCM 8.6.2,

when i run the DHCP as a class C subnet mask everything works fine,

when i try to run the DHCP as a class B, the DHCP stop working.

for example:

Subnet IPv4 Address
Primary Start IPv4 Address
Primary End IPv4 Address
Secondary Start IPv4 Address
Secondary End IPv4 Address
Primary Router IPv4 Address
Secondary Router IPv4 Address
IPv4 Subnet Mask

once i put the subnet as 255.255.255.0 it works.

even i tried to put the subnet as 10.170.0.0 but still it didn't work with class B subnet mask

(I have a license for 1980 units)

[Marc El Achkar]

Subnet IPv4 Address: 10.170.1.0    

Subnet IPv4 Address: 10.170.1.50

Primary End IPv4 Address: 10.170.1.240

IPv4 Subnet Mask: 255.255.0.0

this is in case the IP's are not visible in the above example

and of course the IP of the CUCM is in class B it is 10.170.1.10/16