In recent weeks there has been a long running thread over at the DSL Reports VoIP forum. It revolves around differences in the menus on the handsets the ship as part of a Gigaset C610A IP SIP/DECT phone system vs C610H expansion handset.
The menus on the handset show or hide certain options depending upon how the handset was intended to be delivered. It might deliver as part of a C610A IP system, in which case the menu option to “Select Services” is shown. The handset may be configured to deliver as part of a Gigaset C610A-L410 combination. Since that system is not IP-capable the “Select Services” menu is not shown on the handset.