[Asterisk-Dev] SIP REGISTER -- different values for From and Digest username fields

[Benjamin on Asterisk Mailing Lists]

I'd like to ask for assistance how to patch Asterisk's sip
implementation so that it can construct a SIP REGISTER message where
the From field is different from the username in the digest.

Apparently, this is necessary in order to get Asterisk to register
with NTT who act as a registrar and proxy provider for almost all
Japanese VoIP services (two or three exceptions, none of which work
with Asterisk either).

NTT support staff claims that the From field must be different from
the username in the digest. It seems though that they don't care much
about what the Contact field says. If so, I thought it would be easy
to tie the From field to the value of the Contact field, the setting
of which Asterisk already provides syntax for.

In other words ...

register => DUDEDUDE:blah at ispvoip-9999.ocn.ne.jp/05012345678

... would result in the following ...

REGISTER sip:ispvoip-9999.ocn.ne.jp SIP/2.0
Via: SIP/2.0/UDP 1.2.3.4:5060;branch=z9hG4bK6920ea27
From: <sip:05012345678 at ispvoip-9999.ocn.ne.jp>;tag=as040e1159
To: <sip:05012345678 at ispvoip-9999.ocn.ne.jp>
Call-ID: 30fdde67359f39f04d41ac1b561586f3 at 1.2.3.4
CSeq: 961 REGISTER
Authorization: Digest username="DUDEDUDE", realm="ocn.ne.jp",
algorithm="MD5", uri="sip:210.9.9.9", nonce="1296649548",
response="a2d87gd7015f24bb629a34at18a63b4c", opaque=""
Expires: 120
Contact: <sip:05012345678 at 1.2.3.4>
Event: registration

instead of having both the From field and the username use the same
value as it is now. I think this makes much more sense anyway.

initially this behaviour could be enabled by some #define directive
until somebody finds the time to include some extra syntax in
sip.conf.

an ordinary "register userid at domain.com" (without the optional
/contactid appended) would remain untouched by this either way.

Any help patching the code accordingly would be very much appreciated.

thanks
rgds
benjk

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