not sure what you mean, HA like you have 2 Callservers that make up one HA CS1000, or are you referring to having more than one CS1000 where you either have controlled load sharing or a primary/secondary CS1000's where the secondary is campus or geo redundant backup? Give us an idea what you have.

Yes we have 2 call servers @ 2 locations and operating like DC & DR but sometime client perform the activity @ one location so traffic need to shifted DR location so could you please let know the process how to make active secondary CS.

I am not fully sure but if you re-register the gateways to the secondary Callserver that can be done in LD 135

SMGR xx yy Forces Media Gateway to register on a specified Call
Server, where:
• xx = specified Call Server. Options for this parameter are
PRIM (Primary), ALT1 (Alternate Call Server 1), or ALT2
(Alternate Call Server 2).
• yy = cabinet number of the Media Gateway to be
switched.
Note:
The GRDRC ABKUP prompt must be configured as
SCHD on the primary and alternate system for this
command to work

For IP phones you could just shut down TPS in the Sig Servers at the primary site, Command line "disiTPS" the phone setup would normally be to go to the Secondary System First so should re-register. The GRSC should activate the Secondary server when the registered devices go above the threshold set.

Dear,

I have simple query about cutover means how to make active secondary server.

what version of software are you on?

Release Version 7.6

Then there is test commands to move individual sets etc. but think the commands listed above are what you need. Basically if available the Gateways and phones will try to register at the primary site. The commands above allow you to force over gateways and phones. The secondary Callservers state for going active is in the GRSC config and normally set to a number of gateways and/or a number phones being registered to the system.