Here are two things you can try. Both of them are done on the memory phone or system phone, or using "online mode" in the software.
Dial the following:
*95 31994 78110370
*95 tells the system to go into programming mode
31994 is the default password
78110370 is the country code for US (those are zeroes)
Otherwise, do this from the system phone by the PBX:
(my notes do not show a *95 between *4182 and login, but...)
*4812 (sets phone to English)
31994 (username)
31994 (password)
31994 (pick new password - leave same)
31994 (confirm new password - leave same)
29 (to go to "system" menu)
use --> scroll to init
choose country
save
The first example, to the best of my knowledge is for the oldest versions of the software and the last example is for newer versions of the software. I have worked with 1.0, 2.0 and 3.0 (which is also 150H v1.0).
Hope that helps.