that becomes the IPSEC preshared key field value
when keying the settings into my phone, i have the following fields shown when Type is PPTP (default value)
Name:
Type:
Server Address:
[ ] PPP encryption (MFPS)
[ ] Show advanced options
When i change Type to L2TP/IPSec PSK, i get a new set of fields:
Name:
Type: L2TP/IPSec PSK
Server Address:
L2TP secret: (not used)
IPSec identifier: (not used)
IPSec preshared key: <your secret password>
[ ] Show advanced options
hope that helps 🙂