encountered bad request for calls from asterisk to ser. i can't figure out why?

does ser expect a "user" or port in To: field? failed codec negotiation?

here are the sip messages

Reliably Transmitting:
INVITE sip:kelvin@10.17.0.100 SIP/2.0
Via: SIP/2.0/UDP 10.17.0.100:5065;branch=z9hG4bK580fdaaf
From: "2010" <sip:2010@10.17.0.100:5065>;tag=as0dd619ef
To: <sip:kelvin@10.17.0.100>
Contact: <sip:2010@10.17.0.100:5065>
Call-ID: 20be6f95408969da5117a6b82036d540@10.17.0.100
CSeq: 102 INVITE
User-Agent: Asterisk PBX
Content-Type: application/sdp
Content-Length: 234

v=0
o=root 20301 20301 IN IP4 10.17.0.100
s=session
c=IN IP4 10.17.0.100
t=0 0
m=audio 13602 RTP/AVP 3 0 8 101
a=rtpmap:3 GSM/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
(no NAT) to 10.17.0.100:5060
Sip read:
SIP/2.0 100 trying -- your call is important to us
Via: SIP/2.0/UDP 10.17.0.100:5065;branch=z9hG4bK580fdaaf
From: "2010" <sip:2010@10.17.0.100:5065>;tag=as0dd619ef
To: <sip:kelvin@10.17.0.100>
Call-ID: 20be6f95408969da5117a6b82036d540@10.17.0.100
CSeq: 102 INVITE
Server: Sip EXpress router (0.8.11 (i386/linux))
Content-Length: 0
Warning: 392 10.17.0.100:5060 "Noisy feedback tells: pid=20118 req_src_ip=10.17.0.100 req_src_port=5065 in_uri=sip:kelvin@10.17.0.100 out_uri=sip:10.17.0.30:12532;transport=tcp via_cnt==1"

9 headers, 0 lines
Sip read:
SIP/2.0 400 Bad Request
Via: SIP/2.0/UDP 10.17.0.100:5065;branch=z9hG4bK580fdaaf
From: "2010" <sip:2010@10.17.0.100:5065>;tag=as0dd619ef
To: <sip:kelvin@10.17.0.100>;tag=49dd952c-6360-4555-be16-601328c6805a
Call-ID: 20be6f95408969da5117a6b82036d540@10.17.0.100
CSeq: 102 INVITE
Record-Route: <sip:kelvin@10.17.0.100;transport=tcp;r2=on;ftag=as0dd619ef;lr>
Record-Route: <sip:kelvin@10.17.0.100;r2=on;ftag=as0dd619ef;lr>
User-Agent: Windows RTC/1.0
Content-Length: 0

10 headers, 0 lines
Transmitting:
ACK sip:kelvin@10.17.0.100 SIP/2.0
Via: SIP/2.0/UDP 10.17.0.100:5065;branch=z9hG4bK580fdaaf
From: "2010" <sip:2010@10.17.0.100:5065>;tag=as0dd619ef
To: <sip:kelvin@10.17.0.100>;tag=49dd952c-6360-4555-be16-601328c6805a
Contact: <sip:2010@10.17.0.100:5065>
Call-ID: 20be6f95408969da5117a6b82036d540@10.17.0.100
CSeq: 102 ACK
User-Agent: Asterisk PBX
Content-Length: 0