Possible failure in SIP Outbound proxy handling

Hi,

I'm currently struggling using ekiga as a mobile SIP Client against asterisk 
sip server. (Ubuntu GNOME 14.04 - Ekiga 4.0.1-4)
Following Settings are used:

user: Test User
registrar: asterisk.domain.com
username: testuser
digest username: testuser
password: ********

outbound proxy:  asterisk.domain.com


Aim: I want to call 1234 on the asterisk the account is configured to.

If I enter 'sip:[email protected]' in the dial view the call is placed 
sucessfully.


INVITE sip:[email protected] SIP/2.0
CSeq: 1 INVITE
v: SIP/2.0/UDP 192.168.108.10:5060;branch=z9hG4bK5eef0b0d-849b-
e611-831a-525400123411;rport
User-Agent: Ekiga/4.0.1
f: <sip:[email protected]>;tag=a81f0a0d-849b-
e611-831a-525400123411

INVITE sip:[email protected] SIP/2.0
CSeq: 2 INVITE
v: SIP/2.0/UDP 192.168.108.10:5060;branch=z9hG4bK2ab30d0d-849b-
e611-831a-525400123411;rport
User-Agent: Ekiga/4.0.1
Authorization: Digest username="testuser_mobile", realm="asterisk", 
nonce="23fff1c8", uri="sip:[email protected]", algorithm=MD5, 
response="0bfcf00e82f9a462f7c31581cf79ff45"
f: <sip:[email protected]>;tag=a81f0a0d-849b-
e611-831a-525400123411



But that is very complicated. I can't tell any user, if he wants to place a 
call he has to prepend 'sip:' and append '@asterisk.domain.com'.

So I try to place a call to '1234'. And that fails. The call is send to the 
outbound proxy, but with a completely wrong sip identity.
testuser@localpc instead of [email protected]./
testuser is the local user account.

This is what I see on asterisk console:

[Oct 28 15:57:00] WARNING[5944][C-0002187a]: chan_sip.c:16405 check_auth: 
username mismatch, have <testuser>, digest has <testuser_mobile>
[Oct 28 15:57:00] NOTICE[5944][C-0002187a]: chan_sip.c:25351 
handle_request_invite: Failed to authenticate device 
<sip:[email protected]>;tag=50830510-849b-e611-831a-525400123411



INVITE sip:1234 SIP/2.0
CSeq: 1 INVITE
v: SIP/2.0/UDP 192.168.108.10:5060;branch=z9hG4bK04d20710-849b-
e611-831a-525400123411;rport
User-Agent: Ekiga/4.0.1
f: <sip:[email protected]>;tag=50830510-849b-e611-831a-525400123411

INVITE sip:1234 SIP/2.0
CSeq: 2 INVITE
v: SIP/2.0/UDP 192.168.108.10:5060;branch=z9hG4bKf2690910-849b-
e611-831a-525400123411;rport
User-Agent: Ekiga/4.0.1
Authorization: Digest username="testuser_mobile", realm="asterisk", 
nonce="1b2a334d", uri="sip:1234", algorithm=MD5, 
response="1ac5a8d490e558f4eb0b91449b19f6a1"
f: <sip:[email protected]>;tag=50830510-849b-e611-831a-525400123411


So what should I do  for this case?

Thanks for advice!

Sebastian Himmler