Snom M30 button "line" not shown to choose current outgoing line

The button "line" is not shown on my M30 handset when browsing the global phone book or typing a random number, although i have two identities / lines configured. Changing the default outgoing line is possible and changing it works fine over the settings menu. But its too complicated to always change the outgoing number this way.

Page 56 of User Manual V1.01 for Handset M70/M80/M90/M30:

Changing the identity for the current outgoing call. The default identity will not be changed.
1. Before pressing the green key to dial a number, press the function key underneath Line
(Fig. 3).
◦ When dialing manually: You can do this at any time while or after entering the digits on
the keypad manually.
◦ When calling a number from the global phonebook, select the contact, then press the
function key underneath Line (Fig. 4).
2. Select the extension to be used for the next outgoing call and press the function key
underneath Select (Fig. 1 and 2).
3. When dialing manually, the display will return to the Enter number screen (Fig. 3) where
you can enter any remaining digits, if necessary. When dialing a number from the central
directory, the display will return to the directory page with the number you want to dial (Fig.
4).
4. Press the green key to dial.