With the firmware update 262 for Go Boxes, the behavior of the handsets in ongoing calls has changed. The left display key is now assigned to "Block Call" instead of "Ext. Call". The block call function can be used to end unwanted advertising calls and to add the caller's phone number to the blacklist. 

Initiating consultation calls is no longer possible via this key, but there are other options for initiating a call transfer.

Handsets with a dedicated "R" key can use this key.

Handsets without a dedicated "R" key (e.g. C430H/HX, CL660H/HX, etc.) also have the "0" key assigned to call transfer and can be activated in ongoing calls by pressing and holding it.

In all handsets, it is also possible to press the right display key (Options) during ongoing calls and select "Ext. Call" there.