Howto disable PickUp without disabling subscription?

One from many configurations.
GrandStream GXP2100 GXP2120.
Programmable keys programmed for BLF.
There is no possibility to turn off pickup function on BLF keys from the phone.
GrandStream support insists this is possible from the PBX side.

I see ‘notifycid’ paramert in sip.conf. This in only global parameter. Per peer not works.
Turn it to ‘no’ cause GrandStream not pickup, but dial the number with some prefix, which maybe configured to nothing.
This is what I need. But not global. Just per peer. Or maybe per subscription (hint in extensions.conf).