[asterisk-users] What does this error message mean

[Ira]

I get this when my brother in law tries to call in from his box to mine.

WARNING[4855]: chan_sip.c:12675 check_auth: username mismatch, have 
<100>, digest has <s>

or after changing the register line:

WARNING[4855]: chan_sip.c:12675 check_auth: username mismatch, have 
<100>, digest has <199>

I have done everything I can think of and still failure.

Currently the register line says:

register => name:pass@ 0.0.0.0/199

and there is both a context [199] and [100] in extensions.conf with a 
goto to where I want and thse two lines in the declared context in sip.conf:

exten => 100,1,goto(,,)
exten => 199,1,goto(,,)

I'm sure I'll feel quite silly when the error of my ways is pointed 
out, but for the moment I'm stumped.

Ira