pppd: In file /etc/ppp/peers/1xevdo: unrecognized option '/dev/ttyUSB0'
What do you do to elicit this response? You are not just sitting there minding your own business, you did something: what was it?
pppd is not normally appropriate for a wireless card - however, sierra have set their cards to interface as if they were dailup modems (shudder). Don't know if this extends to the current GPL drivers though.
MP595 is supported. Don't know if this includes the 595u though.
Kernel 2.6.23+ includes the drivers and patches.
The site has a warning:
IMPORTANT!! If you have a CDMA device and it has not yet been activated you must first use the device on a Windows system with the supplied connection manager. Some carriers do pre-activation, however it is still recommended to first try the device on a Windows machine.
... check with your carrier. Do they do pre-activation?
What does "modinfo sierra" tell you?
What does "pppd call CDMA" tell you?
Funny... suspect your modem is at /dev/USB/ttyUSB1
These devices are only created while the modem is present and detected, so ls /dev/ttyU* should give you a list.
If none are present (they are normally a link to /dev/USBx anyway) then point pppd at the existing /dev/USB0,1,2,3... etc until you get a hit.