Usual nat_uac_test with numbers 19 and 3 does not seems to detect is behind nat so NATMANAGE is not called

Here its some trace. ANy clue how to handle this phones if they activate STUN for example

U 80.26.x.x:52768 -> 192.168.0.170:8002

INVITE sip:2@x.x.x.x:8002 SIP/2.0.

Via: SIP/2.0/UDP 80.26.x.x:52768;branch=z9hG4bK358742535;rport.

From: "Anonymous" <sip:anonymous@anonymous.invalid>;tag=1478444456.

To: <sip:2@x.x.x.x:8002>.

Call-ID: 244257786-52768-56@IA.CG.BIE.BCH.

CSeq: 550 INVITE.

Contact: "Anonymous" <sip:212@80.26.x.x:52768>.

X-Grandstream-PBX: true.

Max-Forwards: 70.

User-Agent: Grandstream GXP2140 1.0.4.23.

Privacy: id.

P-Preferred-Identity: <sip:212@x.x.x.x:8002>.

Supported: replaces, path, timer.

Allow: INVITE, ACK, OPTIONS, CANCEL, BYE, SUBSCRIBE, NOTIFY, INFO, REFER, UPDATE, MESSAGE.

Content-Type: application/sdp.

Accept: application/sdp, application/dtmf-relay.

Content-Length:   335.

.

v=0.

o=212 8000 8000 IN IP4 80.26.x.x.

s=SIP Call.

c=IN IP4 80.26.x.x.

t=0 0.

m=audio 55422 RTP/AVP 0 8 18 9 2 101.

a=sendrecv.

a=rtpmap:0 PCMU/8000.

a=ptime:20.

a=rtpmap:8 PCMA/8000.

a=rtpmap:18 G729/8000.

a=fmtp:18 annexb=no.

a=rtpmap:9 G722/8000.

a=rtpmap:2 G726-32/8000.

a=rtpmap:101 telephone-event/8000.

a=fmtp:101 0-15.

# Caller NAT detection route

route[NATDETECT] {

#!ifdef WITH_NAT

        force_rport();

        if (nat_uac_test("19)) {

                if (is_method("REGISTER")) {

                        fix_nated_register();

                } else {

                        fix_nated_contact();

                }

                setflag(FLT_NATS);

}

#!endif

        return;

}