[Asterisk-Users] Strange Fromuser behavior?

[E. Versaevel]

Strange things are happening at my asterisk box :)
I've got asterisk setup to dail out with sip to my SIP provider.
I've got NO fromuser/fromdomain stuff setup in my sip.conf

When I place a call with my Siemens Optipoint 400 SIP phone everything is
allright, the From: header is stating the username of the Siemens phone.
When I place a call with X-Lite the From: header is altered and reads
asterisk at host instead of X-Liteusername at host.

Any idea how this is possible?

Kind reagards,

E. Versaevel