Echo App: ERROR: decode() returned 0

[abdoulosseni]

Hello,
I try to test "echo" app.

Kamailio configuration:
remove_hf("P-App-Name"); append_hf("P-App-Name: echo\r\n");

Sems Version:
Sip Express Media Server (1.6.0 (x86_64/linux))

For each call, I got this log:
[receive, AmRtpAudio.cpp:212] ERROR: decode() returned 0

Here is my Invite from the SIP phone:
`INVITE sip:[email protected]:5060 SIP/2.0
Via: SIP/2.0/UDP x.x.x.x;branch=z9hG4bKa458.45736f6696f19ac67a314a0ec90f8911.0;i=a61
From: sip:[email protected];tag=NjHoESHr
To: "200" sip:[email protected]
CSeq: 20 INVITE
Call-ID: iIDgzXk8C
Max-Forwards: 69
Supported: replaces, outbound
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE, SUBSCRIBE, INFO, UPDATE
Content-Type: application/sdp
Content-Length: 384
User-Agent: Africallshop_iPhone.SE_iOS11.4/4ec3330 (belle-sip/1.4.2)
P-App-Name: echo
Contact: sip:[email protected]

v=0
o=5b38f3db65741_2 877 1151 IN IP4 x.x.x.x
s=Talk
c=IN IP4 x.x.x.x
b=AS:380
t=0 0
a=rtcp-xr:rcvr-rtt=all:10000 stat-summary=loss,dup,jitt,TTL voip-metrics
m=audio 31658 RTP/AVP 96 0 8 101
a=rtcp-fb:* trr-int 5000
a=rtpmap:96 speex/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:96 vbr=on
a=sendrecv
a=rtcp:31659`

Regards
Abdoul