Strange SIP packet

Hi, everyone.
I’m testing a SIP cable modem with asterisk. The REGISTER packet it sends has varios “Authorization” sections, which I have never seen before. Asterisk sends back “401 Unauthorized”. I’ve checked username and password both in cable modem config and in asterisk sip.conf. They are correct. So, is the reason for “401 Unauthorized” those multiple “Authorization” sections? If anyone is more less familiar with SIP, please could you take a look at the packet trace below. Is it ok?
Thanks in advance.

15:06:48.346157 IP 10.2.0.63.5060 > 192.168.0.4.5060: UDP, length 1345
E…]…?.O.
…?..I".REGISTER sip:192.168.0.4 SIP/2.0
From: 968953939sip:968953939@localhost;tag=94b7ef58-a02003f-13c4-45026-20-3eb775bd-20
To: 968953939sip:968953939@localhost
Call-ID: 94b7b630-a02003f-13c4-45026-20-6733142f-20
CSeq: 9898 REGISTER
Via: SIP/2.0/UDP 10.2.0.63:5060;branch=z9hG4bK-63b06-185692fe-78a7e24
Max-Forwards: 70
Supported: timer,replaces,join,100rel
User-Agent: ARRIS-TM501B release v.05.02.0X SN/0015960DBC24
Contact: 968953939sip:968953939@10.2.0.63:5060
Authorization: Digest username=“968953939”,realm=“asterisk”,nonce=“5e8e5c3a”,uri=“sip:192.168.0.4”,response=“918f7f23dd8ae8e8fc9465940e8914db”,algorithm=MD5
Authorization: Digest username=“968953939”,realm=“asterisk”,nonce=“5f3ff920”,uri=“sip:192.168.0.4”,response=“d3acf42b9afa65708936b525bb912f36”,algorithm=MD5
Authorization: Digest username=“968953939”,realm=“asterisk”,nonce=“60b3eb72”,uri=“sip:192.168.0.4”,response=“715c6da5586490ee90f16b39f57b98ac”,algorithm=MD5
Authorization: Digest username=“968953939”,realm=“asterisk”,nonce=“637cb9c0”,uri=“sip:192.168.0.4”,response=“49a55de9aab1776c1f7f081465a8c593”,algorithm=MD5
Authorization: Digest username=“968953939”,realm=“asterisk”,nonce=“2d73aae7”,uri=“sip:192.168.0.4”,response=“1dd245c05ade19d7d4fc85c21e5e86fe”,algorithm=MD5
Allow: INVITE,ACK,BYE,CANCEL,NOTIFY,PRACK,UPDATE,OPTIONS
Content-Length: 0