i think i encountered something like a bug in chan_sip (asterisk 1.4.21.2 stable). i have here a registration from 2 clients, one x-lite and the other asterisk both registering to a ZTE softswitch.

i did "pedantic=yes" in sip.conf but it is not registered.
fromdomain=IP-ZTE
fromuser=98681430
host=IP-ZTE
pedantic=yes
secret=Secret
type=peer
username=98681430

here is the x-lite register:

[08-09-17]00:00:17.237 | Info | RESIP:DUM | "Got: SipResp: 200 tid=ed7f62589e032649 cseq=REGISTER contact=98681430@192.168.178.21:25518 / 2 from(wire)" | 
[08-09-17]00:00:17.237 | Info | RESIP:DUM | "Removing binding" | 
[08-09-17]00:00:17.556 | Info | RESIP:DUM | "Got: SipResp: 401 tid=9142c4591c415a3d cseq=REGISTER / 3 from(wire)" | 
[08-09-17]00:00:17.879 | Info | RESIP:DUM | "Got: SipResp: 200 tid=da446b6086014754 cseq=REGISTER / 4 from(wire)" | 
[08-09-17]00:00:17.879 | Info | RESIP:DUM | "Finished removing registration ClientRegistration sip:98681430@IP-ZTE mEndWhenDone=0" | 
[08-09-17]00:00:17.879 | Info | RESIP:DUM | "Sending queued request: REGISTER sip:IP-ZTE SIP/2.0
Via: SIP/2.0/ ;branch=z9hG4bK-d8754z-da446b6086014754-1---d8754z-;rport
Max-Forwards: 70
Contact: <sip:98681430@IP-DSL:25518;rinstance=9a8ebc3de66d045d>
To: ""G-Mobile""<sip:98681430@IP-ZTE>
From: ""G-Mobile""<sip:98681430@IP-ZTE>;tag=ae491c4b
Call-ID: MDcwNDA5OTM5NDFkN2M0MGRiY2Y4YjY5ZTBjYjUyOTg.
CSeq: 5 REGISTER
Expires: 3600
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE, SUBSCRIBE, INFO
User-Agent: X-Lite release 1100l stamp 47546
Authorization: Digest username=""98681430"",realm="""",nonce=""e0b8456a36cf57b0bf10d835244d8ad2"",uri=""sip:IP-ZTE"",response=""e416fbee39a9ed3765bba22c8f26b534"",algorithm=MD5
Content-Length: 0

for the xlite registering to zte softswitch, everythings ok. but take a look at this trace where asterisk 1.4.21.2 is registering to zte softswitch.


REGISTER 12 headers, 0 lines
Reliably Transmitting (no NAT) to IP-ZTE:5060:
REGISTER sip:IP-ZTE SIP/2.0
Via: SIP/2.0/UDP IP-Asterisk:5060;branch=z9hG4bK30ac4235;rport
From: <sip:98681430@IP-ZTE>;tag=as73b24e7e
To: <sip:98681430@IP-ZTE>
Call-ID: 57af94c379000780227ebe0b715014d9@IP-Asterisk
CSeq: 118 REGISTER
User-Agent: Asterisk PBX
Max-Forwards: 70
Expires: 120
Contact: <sip:98681430@IP-Asterisk>
Event: registration
Content-Length: 0


<--- SIP read from IP-ZTE:5060 --->
SIP/2.0 401 Unauthorized
Via: SIP/2.0/UDP IP-Asterisk:5060;received=IP-Asterisk;rport=5060;branch=z9hG4bK30ac4235
To: <sip:98681430@IP-ZTE>
From: <sip:98681430@IP-ZTE>;tag=as73b24e7e
Call-ID: 57af94c379000780227ebe0b715014d9@IP-Asterisk CSeq: 118 REGISTER
User-Agent: ZTE-SoftSwitch
WWW-Authenticate: Digest realm="",
nonce="5e527958cfb8005ef60c415f765785d1",
ZTE-ID=43be83566ad75797738decb0acb2c5e2
Content-Length: 0


Reliably Transmitting (no NAT) to IP-ZTE:5060:
REGISTER sip:IP-ZTE SIP/2.0
Via: SIP/2.0/UDP IP-Asterisk:5060;branch=z9hG4bK7d336ee3;rport
From: <sip:98681430@IP-ZTE>;tag=as5c337b97
To: <sip:98681430@IP-ZTE>
Call-ID: 57af94c379000780227ebe0b715014d9@IP-Asterisk
CSeq: 119 REGISTER
User-Agent: Asterisk PBX
Max-Forwards: 70
Authorization: Digest username="98681430", realm="", algorithm=MD5, uri="sip:IP-ZTE", nonce="", response="27aa0453f982dbc7d3fd88d0dca09efb", opaque=""
Expires: 120
Contact: <sip:98681430@IP-Asterisk>
Event: registration
Content-Length: 0

<--- SIP read from IP-ZTE:5060 --->
SIP/2.0 401 Unauthorized
Via: SIP/2.0/UDP IP-Asterisk:5060;received=IP-Asterisk;rport=5060;branch=z9hG4bK7d336ee3
To: <sip:98681430@IP-ZTE>
From: <sip:98681430@IP-ZTE>;tag=as5c337b97
Call-ID: 57af94c379000780227ebe0b715014d9@IP-Asterisk
CSeq: 119 REGISTER
User-Agent: ZTE-SoftSwitch
WWW-Authenticate: Digest realm="",
nonce="5e527958cfb8005ef60c415f765785d1",
ZTE-ID=43be83566ad75797738decb0acb2c5e2
Content-Length: 0