"無會話，非5G”鏈接如下：https://mp.weixin.qq.com/s/AX3MCn1woaSRrDVd2nkrtA
VoLTE測試中繞不開的一項就是MOS；它是對VOLTE語音質(zhì)量的評估，根據(jù)中移評估標(biāo)準(zhǔn)其最高值為5.0；而決定MOS值的是通話中編碼（Codec）選擇和更新；
1.編碼（Codec）選擇和更新
在VoLTE和Video通話中,編碼（Codec）的選擇和配置是在會話建立或通話中根據(jù)主、被叫協(xié)商情況結(jié)果，通過SDP(Session Description Protocol)執(zhí)行的；如下表所示：
2.SDP相關(guān)內(nèi)容(以下示例紅色字體部分）
2.1 INVITE
INVITE sip:0123456789;phone-context=test.net@test.net;user=phone SIP/2.0
Allow: INVITE,ACK,OPTIONS,CANCEL,BYE,UPDATE,INFO,REFER,NOTIFY,MESSAGE,PRACK
P-Preferred-Identity: <sip:310410123456789@test.net>
User-Agent: TEST IMS CLIENT 4.0
P-Preferred-Service: urn:urn-7:3gpp-service.ims.icsi.mmtel
CSeq: 1 INVITE
Max-Forwards: 70
P-Access-Network-Info: 3GPP-E-UTRAN-FDD;utran-cell-id-3gpp=31041000010000000
Route: <sip:[2001:0:0:2::2]:5060;lr>
a: *;+g.3gpp.icsi-ref="urn%3Aurn-7%3A3gpp-service.ims.icsi.mmtel"
c: application/sdp
f: <sip:310410123456789@test.net>;tag=2763466811
i: 2270680280
k: 100rel,timer,precondition
l: 733
m: <sip:310410123456789@[2001:0:0:2::1]:5060;transport=UDP>;+g.3gpp.icsi-ref="urn%3Aurn-7%3A3gpp-service.ims.icsi.mmtel"
t: <sip:0123456789;phone-context=test.net@test.net;user=phone>
v: SIP/2.0/TCP [2001:0:0:2::1]:5060;branch=z9hG4bK932432170smg;transport=TCP
v=0
o=TEST-IMS-UE 1234562 0 IN IP6 2001:0:0:2::1
s=SS VOIP
c=IN IP6 2001:0:0:2::1
t=0 0
m=audio 50000 RTP/AVP 116 107 97 115 111 110
b=AS:49
a=rtpmap:116 AMR-WB/16000
a=fmtp:116 mode-change-capability=2; max-red=0
a=rtpmap:107 AMR-WB/16000
a=fmtp:107 octet-align=1;mode-change-capability=2; max-red=0
a=rtpmap:97 AMR/8000
a=fmtp:97 mode-change-capability=2; max-red=0
a=rtpmap:115 AMR/8000
a=fmtp
2.2 100 Trying
SIP/2.0 100 Trying
Via: SIP/2.0/TCP [2001:0:0:2::1]:5060;branch=z9hG4bK932432170smg;transport=TCP
Max-Forwards: 70
From: <sip:310410123456789@test.net>;tag=2763466811
To: <sip:0123456789;phone-context=test.net@test.net;user=phone>
Call-ID: 2270680280
CSeq: 1 INVITE
Content-Length: 0
2.3 183 Session Progress
SIP/2.0 183 Session Progress
Max-Forwards: 70
Via: SIP/2.0/TCP [2001:0:0:2::1]:5060;branch=z9hG4bK932432170smg;transport=TCP
From: <sip:310410123456789@test.net>;tag=2763466811
To: <sip:0123456789;phone-context=test.net@test.net;user=phone>;tag=1111111111
Call-ID: 2270680280
CSeq: 1 INVITE
Contact: <sip:0123456789@[2001:0:0:2::2]:65094;transport=tcp>
Record-Route: <sip:[2001:0:0:2::2];lr>
Content-Type: application/sdp
Require: precondition
Require: 100rel
RSeq: 1
Content-Length: 763
Privacy: none
P-Asserted-Identity: <sip:0123456789>;phone-context=test.net@test.net;user=phone
v=0
o=anritsu 1 1 IN IP6 2001:0:0:2::2
s=SS VOIP
c=IN IP6 2001:0:0:2::2
t=0 0
m=audio 60000 RTP/AVP 116 107 97 115 111 110
b=AS:49
a=rtpmap:116 AMR-WB/16000
a=fmtp:116 mode-change-capability=2; max-red=0
a=rtpmap:107 AMR-WB/16000
a=fmtp:107 octet-align=1;mode-change-capability=2; max-red=0
a=rtpmap:97 AMR/8000
a=fmtp:97 mode-change-capability=2; max-red=0
a=rtpmap:115 AMR/8000
a=fmtp:115 octet-align=1;mode-change-capability=2; max-red=0
a=rtpmap:111 telephone-event/16000
a=fmtp:111 0-15
a=rtpmap:110 telephone-event/8000
a=fmtp:110 0-15
a=curr:qos local none
a=curr:qos remote none
a=des:qos mandatory local sendrecv
a=des:qos mandatory remote sendrecv
a=sendrecv
a=ptime:20
a=maxptime:240
a=conf:qos remote sendrecv
a=rtcp:60001
2.5 200 OK
SIP/2.0 200 OK
Max-Forwards: 70
Via: SIP/2.0/TCP [2001:0:0:2::1]:5060;branch=z9hG4bK1835967788smg;transport=TCP
From: <sip:310410123456789@test.net>;tag=2763466811
To: <sip:0123456789;phone-context=test.net@test.net;user=phone>;tag=1111111111
Call-ID: 2270680280
CSeq: 3 UPDATE
Allow: INVITE, ACK, CANCEL, BYE, PRACK, MESSAGE
Contact: <sip:0123456789@[2001:0:0:2::2]:65094;transport=tcp>
Record-Route: <sip:[2001:0:0:2::2];lr>
Content-Type: application/sdp
Content-Length: 743
Privacy: none
v=0
o=anritsu 1 2 IN IP6 2001:0:0:2::2
s=SS VOIP
c=IN IP6 2001:0:0:2::2
t=0 0
m=audio 60000 RTP/AVP 116 107 97 115 111 110
b=AS:49
a=rtpmap:116 AMR-WB/16000
a=fmtp:116 mode-change-capability=2; max-red=0
a=rtpmap:107 AMR-WB/16000
a=fmtp:107 octet-align=1;mode-change-capability=2; max-red=0
a=rtpmap:97 AMR/8000
a=fmtp:97 mode-change-capability=2; max-red=0
a=rtpmap:115 AMR/8000
a=fmtp:115 octet-align=1;mode-change-capability=2; max-red=0
a=rtpmap:111 telephone-event/16000
a=fmtp:111 0-15
a=rtpmap:110 telephone-event/8000
a=fmtp:110 0-15
a=curr:qos local sendrecv
a=curr:qos remote sendrecv
a=des:qos mandatory local sendrecv
a=des:qos mandatory remote sendrecv
a=sendrecv
a=ptime:20
a=maxptime:240
a=rtcp:60001
2.6 UPDATE
SIUPDATE sip:0123456789@[2001:0:0:2::2]:65094;transport=TCP SIP/2.0
Proxy-Require: sec-agree
Security-Verify:
CSeq: 3 UPDATE
Max-Forwards: 70
P-Access-Network-Info: 3GPP-E-UTRAN-FDD;utran-cell-id-3gpp=31041000010000000
Route: <sip:[2001:0:0:2::2];lr>
c: application/sdp
f: <sip:310410123456789@test.net>;tag=2763466811
i: 2270680280
l: 738
m: <sip:310410123456789@[2001:0:0:2::1]:5060;transport=UDP>
t: <sip:0123456789;phone-context=test.net@test.net;user=phone>;tag=1111111111
v: SIP/2.0/TCP [2001:0:0:2::1]:5060;branch=z9hG4bK1835967788smg;transport=TCP
v=0
o=TEST-IMS-UE 1234562 1 IN IP6 2001:0:0:2::1
s=SS VOIP
c=IN IP6 2001:0:0:2::1
t=0 0
m=audio 50000 RTP/AVP 116 107 97 115 111 110
b=AS:49
a=rtpmap:116 AMR-WB/16000
a=fmtp:116 mode-change-capability=2; max-red=0
a=rtpmap:107 AMR-WB/16000
a=fmtp:107 octet-align=1;mode-change-capability=2; max-red=0
a=rtpmap:97 AMR/8000
a=fmtp:97 mode-change-capability=2; max-red=0
a=rtpmap:115 AMR/8000
a=fmtp:115 octet-align=1;mode-change-capability=2; max-red=0
a=rtpmap:111 telephone-event/16000
a=fmtp:111 0-15
a=rtpmap:110 telephone-event/8000
a=fmtp:110 0-15
a=curr:qos local sendrecv
a=curr:qos remote none
a=des:qos mandatory local sendrecv
a=des:qos mandatory remote sendrecv
a=sendrecv
a=ptime:20
a=maxptime:240
2.7 200 OK
SIP/2.0 200 OK
Max-Forwards: 70
Via: SIP/2.0/TCP [2001:0:0:2::1]:5060;branch=z9hG4bK1835967788smg;transport=TCP
From: <sip:310410123456789@test.net>;tag=2763466811
To: <sip:0123456789;phone-context=test.net@test.net;user=phone>;tag=1111111111
Call-ID: 2270680280
CSeq: 3 UPDATE
Allow: INVITE, ACK, CANCEL, BYE, PRACK, MESSAGE
Contact: <sip:0123456789@[2001:0:0:2::2]:65094;transport=tcp>
Record-Route: <sip:[2001:0:0:2::2];lr>
Content-Type: application/sdp
Content-Length: 743
Privacy: none
v=0
o=anritsu 1 2 IN IP6 2001:0:0:2::2
s=SS VOIP
c=IN IP6 2001:0:0:2::2
t=0 0
m=audio 60000 RTP/AVP 116 107 97 115 111 110
b=AS:49
a=rtpmap:116 AMR-WB/16000
a=fmtp:116 mode-change-capability=2; max-red=0
a=rtpmap:107 AMR-WB/16000
a=fmtp:107 octet-align=1;mode-change-capability=2; max-red=0
a=rtpmap:97 AMR/8000
a=fmtp:97 mode-change-capability=2; max-red=0
a=rtpmap:115 AMR/8000
a=fmtp:115 octet-align=1;mode-change-capability=2; max-red=0
a=rtpmap:111 telephone-event/16000
a=fmtp:111 0-15
a=rtpmap:110 telephone-event/8000
a=fmtp:110 0-15
a=curr:qos local sendrecv
a=curr:qos remote sendrecv
a=des:qos mandatory local sendrecv
a=des:qos mandatory remote sendrecv
a=sendrecv
a=ptime:20
a=maxptime:240
a=rtcp:60001
。。。。。。。。
原文來自：http://www.sharetechnote.com/
整理：kangguoying20200928
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