[Kamailio-Users] Loadbalancer/outbound_proxy and ACK problem

Daniel-Constantin Mierla miconda at gmail.com
Fri Mar 12 16:21:09 CET 2010 

Hello,

very likely you use fix natted contact in reg+proxy. You have to use 
that in load balancer, since that is the instance that sees the right 
public ip address for UA. reg+proxy will see IP address of LB as being 
source IP address.

Cheers,
Daniel


On 03/12/2010 12:15 PM, Pavel Miskov wrote:
> Hello Inaki,
>
> thanks for replying and here is more readable form taken from LB:
>
> Pavel
>
> #
> U +0.000000 UAC_A_PUB_IP:31488 ->  LB_IP:5678
> INVITE sip:UAC_B at test.com SIP/2.0.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;branch=z9hG4bK-d8754z-a9127351d94a483a-1---d8754z-;rport.
> Max-Forwards: 70.
> Contact:<sip:UAC_A at UAC_A_PRIV_IP:31488>.
> To: "UAC_B"<sip:UAC_B at test.com>.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 INVITE.
> Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE,
> SUBSCRIBE, INFO.
> Content-Type: application/sdp.
> Proxy-Authorization: Digest
> username="UAC_A",realm="test.com",nonce="4b9a102f000000030feed796808fa4eb1df2de3c9a2b1034",uri="sip:UAC_B at test.com",response="2f023b974dd4cde6f29387681168de8f",algorithm=MD5.
> User-Agent: X-Lite release 1100l stamp 47546.
> Content-Length: 368.
>
>
> #
> U +0.004000 LB_IP:5678 ->  UAC_A_PUB_IP:31488
> SIP/2.0 100 Giving a try.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;branch=z9hG4bK-d8754z-a9127351d94a483a-1---d8754z-;rport=31488;received=UACs_PUB_IP.
> To: "UAC_B"<sip:UAC_B at test.com>.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 INVITE.
> Server: Kamailio (1.5.1-tls (x86_64/linux)).
> Content-Length: 0.
> .
>
> #
> U +0.000000 LB_IP:5678 ->  REG_PROXY_IP:5166
> INVITE sip:UAC_B at test.com SIP/2.0.
> Record-Route:<sip:LB_IP:5678;lr=on>.
> Via: SIP/2.0/UDP LB_IP:5678;branch=z9hG4bK3ae9.a8d68282.0.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;received=UACs_PUB_IP;branch=z9hG4bK-d8754z-a9127351d94a483a-1---d8754z-;rport=31488.
> Max-Forwards: 69.
> Contact:<sip:UAC_A at UAC_A_PUB_IP:31488>.
> To: "UAC_B"<sip:UAC_B at test.com>.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 INVITE.
> Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE,
> SUBSCRIBE, INFO.
> Content-Type: application/sdp.
> Proxy-Authorization: Digest
> username="UAC_A",realm="test.com",nonce="4b9a102f000000030feed796808fa4eb1df2de3c9a2b1034",uri="sip:UAC_B at test.com",response="2f023b974dd4cde6f29387681168de8f",algorithm=MD5.
> User-Agent: X-Lite release 1100l stamp 47546.
> Content-Length: 368.
> Path:<sip:LB_IP:5678;lr>.
> .
>
>
> #
> U +0.000000 REG_PROXY_IP:5166 ->  LB_IP:5678
> SIP/2.0 100 Giving a try.
> Via: SIP/2.0/UDP LB_IP:5678;branch=z9hG4bK3ae9.a8d68282.0.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;received=UACs_PUB_IP;branch=z9hG4bK-d8754z-a9127351d94a483a-1---d8754z-;rport=31488.
> To: "UAC_B"<sip:UAC_B at test.com>.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 INVITE.
> Server: Kamailio (1.5.1-tls (x86_64/linux)).
> Content-Length: 0.
> .
>
> #
> U +0.000000 REG_PROXY_IP:5166 ->  LB_IP:5678
> INVITE sip:UAC_B at UAC_B_PRIV_IP:31468;rinstance=06b43c2b0e1ae81a SIP/2.0.
> Record-Route:<sip:REG_PROXY_IP:5166;lr=on;nat=yes>.
> Record-Route:<sip:LB_IP:5678;lr=on>.
> Via: SIP/2.0/UDP REG_PROXY_IP:5166;branch=z9hG4bK3ae9.ff046b92.0.
> Via: SIP/2.0/UDP LB_IP:5678;branch=z9hG4bK3ae9.a8d68282.0.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;received=UACs_PUB_IP;branch=z9hG4bK-d8754z-a9127351d94a483a-1---d8754z-;rport=31488.
> Route:<sip:LB_IP:5678;lr;received="sip:UAC_B_PUB_IP:31468">.
> Max-Forwards: 68.
> Contact:<sip:UAC_A at UAC_A_PUB_IP:31488>.
> To: "UAC_B"<sip:UAC_B at test.com>.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 INVITE.
> Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE,
> SUBSCRIBE, INFO.
> Content-Type: application/sdp.
> User-Agent: X-Lite release 1100l stamp 47546.
> Content-Length: 384.
> Path:<sip:LB_IP:5678;lr>.
> .
>
> #
> U +0.032000 LB_IP:5678 ->  REG_PROXY_IP:5166
> SIP/2.0 100 Giving a try.
> Via: SIP/2.0/UDP
> REG_PROXY_IP:5166;branch=z9hG4bK3ae9.ff046b92.0;rport=5166;received=REG_PROXY_IP.
> Via: SIP/2.0/UDP LB_IP:5678;branch=z9hG4bK3ae9.a8d68282.0.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;received=UACs_PUB_IP;branch=z9hG4bK-d8754z-a9127351d94a483a-1---d8754z-;rport=31488.
> To: "UAC_B"<sip:UAC_B at test.com>.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 INVITE.
> Server: Kamailio (1.5.1-tls (x86_64/linux)).
> Content-Length: 0.
> .
>
> #
> U +0.000000 LB_IP:5678 ->  UAC_B_PUB_IP:31468
> INVITE sip:UAC_B at UAC_B_PRIV_IP:31468;rinstance=06b43c2b0e1ae81a SIP/2.0.
> Record-Route:<sip:REG_PROXY_IP:5166;lr=on;nat=yes>.
> Record-Route:<sip:LB_IP:5678;lr=on>.
> Via: SIP/2.0/UDP LB_IP:5678;branch=z9hG4bK3ae9.b8d68282.0.
> Via: SIP/2.0/UDP
> REG_PROXY_IP:5166;rport=5166;received=REG_PROXY_IP;branch=z9hG4bK3ae9.ff046b92.0.
> Via: SIP/2.0/UDP LB_IP:5678;branch=z9hG4bK3ae9.a8d68282.0.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;received=UACs_PUB_IP;branch=z9hG4bK-d8754z-a9127351d94a483a-1---d8754z-;rport=31488.
> Max-Forwards: 67.
> Contact:<sip:UAC_A at UAC_A_PUB_IP:31488>.
> To: "UAC_B"<sip:UAC_B at test.com>.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 INVITE.
> Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE,
> SUBSCRIBE, INFO.
> Content-Type: application/sdp.
> User-Agent: X-Lite release 1100l stamp 47546.
> Content-Length: 384.
> Path:<sip:LB_IP:5678;lr>.
> .
>
> #
> U +0.104000 UAC_B_PUB_IP:31468 ->  LB_IP:5678
> SIP/2.0 180 Ringing.
> Via: SIP/2.0/UDP LB_IP:5678;branch=z9hG4bK3ae9.b8d68282.0.
> Via: SIP/2.0/UDP
> REG_PROXY_IP:5166;rport=5166;received=REG_PROXY_IP;branch=z9hG4bK3ae9.ff046b92.0.
> Via: SIP/2.0/UDP LB_IP:5678;branch=z9hG4bK3ae9.a8d68282.0.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;received=UACs_PUB_IP;branch=z9hG4bK-d8754z-a9127351d94a483a-1---d8754z-;rport=31488.
> Record-Route:<sip:REG_PROXY_IP:5166;lr;nat=yes>.
> Record-Route:<sip:LB_IP:5678;lr=on>.
> Contact:<sip:UAC_B at UAC_B_PRIV_IP:31468;rinstance=06b43c2b0e1ae81a>.
> To: "UAC_B"<sip:UAC_B at test.com>;tag=d6775b48.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 INVITE.
> User-Agent: X-Lite release 1100l stamp 47546.
> Content-Length: 0.
> .
>
> #
> U +0.000000 LB_IP:5678 ->  REG_PROXY_IP:5166
> SIP/2.0 180 Ringing.
> Via: SIP/2.0/UDP
> REG_PROXY_IP:5166;rport=5166;received=REG_PROXY_IP;branch=z9hG4bK3ae9.ff046b92.0.
> Via: SIP/2.0/UDP LB_IP:5678;branch=z9hG4bK3ae9.a8d68282.0.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;received=UACs_PUB_IP;branch=z9hG4bK-d8754z-a9127351d94a483a-1---d8754z-;rport=31488.
> Record-Route:<sip:REG_PROXY_IP:5166;lr;nat=yes>.
> Record-Route:<sip:LB_IP:5678;lr=on>.
> Contact:<sip:UAC_B at UAC_B_PRIV_IP:31468;rinstance=06b43c2b0e1ae81a>.
> To: "UAC_B"<sip:UAC_B at test.com>;tag=d6775b48.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 INVITE.
> User-Agent: X-Lite release 1100l stamp 47546.
> Content-Length: 0.
> .
>
> #
> U +0.004000 REG_PROXY_IP:5166 ->  LB_IP:5678
> SIP/2.0 180 Ringing.
> Via: SIP/2.0/UDP LB_IP:5678;branch=z9hG4bK3ae9.a8d68282.0.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;received=UACs_PUB_IP;branch=z9hG4bK-d8754z-a9127351d94a483a-1---d8754z-;rport=31488.
> Record-Route:<sip:REG_PROXY_IP:5166;lr;nat=yes>.
> Record-Route:<sip:LB_IP:5678;lr=on>.
> Contact:<sip:UAC_B at LB_IP:5678;rinstance=06b43c2b0e1ae81a>.
> To: "UAC_B"<sip:UAC_B at test.com>;tag=d6775b48.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 INVITE.
> User-Agent: X-Lite release 1100l stamp 47546.
> Content-Length: 0.
> .
>
> #
> U +0.000000 LB_IP:5678 ->  UAC_A_PUB_IP:31488
> SIP/2.0 180 Ringing.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;received=UACs_PUB_IP;branch=z9hG4bK-d8754z-a9127351d94a483a-1---d8754z-;rport=31488.
> Record-Route:<sip:REG_PROXY_IP:5166;lr;nat=yes>.
> Record-Route:<sip:LB_IP:5678;lr=on>.
> Contact:<sip:UAC_B at LB_IP:5678;rinstance=06b43c2b0e1ae81a>.
> To: "UAC_B"<sip:UAC_B at test.com>;tag=d6775b48.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 INVITE.
> User-Agent: X-Lite release 1100l stamp 47546.
> Content-Length: 0.
> .
>
> #
> U +0.732000 UAC_B_PUB_IP:31468 ->  LB_IP:5678
> SIP/2.0 200 OK.
> Via: SIP/2.0/UDP LB_IP:5678;branch=z9hG4bK3ae9.b8d68282.0.
> Via: SIP/2.0/UDP
> REG_PROXY_IP:5166;rport=5166;received=REG_PROXY_IP;branch=z9hG4bK3ae9.ff046b92.0.
> Via: SIP/2.0/UDP LB_IP:5678;branch=z9hG4bK3ae9.a8d68282.0.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;received=UACs_PUB_IP;branch=z9hG4bK-d8754z-a9127351d94a483a-1---d8754z-;rport=31488.
> Record-Route:<sip:REG_PROXY_IP:5166;lr;nat=yes>.
> Record-Route:<sip:LB_IP:5678;lr=on>.
> Contact:<sip:UAC_B at UAC_B_PRIV_IP:31468;rinstance=06b43c2b0e1ae81a>.
> To: "UAC_B"<sip:UAC_B at test.com>;tag=d6775b48.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 INVITE.
> Session-Expires: 95;refresher=uas.
> Min-SE: 90.
> Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE,
> SUBSCRIBE, INFO.
> Content-Type: application/sdp.
> Supported: timer.
> User-Agent: X-Lite release 1100l stamp 47546.
> Content-Length: 364.
> .
>
> #
> U +0.000000 LB_IP:5678 ->  REG_PROXY_IP:5166
> SIP/2.0 200 OK.
> Via: SIP/2.0/UDP
> REG_PROXY_IP:5166;rport=5166;received=REG_PROXY_IP;branch=z9hG4bK3ae9.ff046b92.0.
> Via: SIP/2.0/UDP LB_IP:5678;branch=z9hG4bK3ae9.a8d68282.0.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;received=UACs_PUB_IP;branch=z9hG4bK-d8754z-a9127351d94a483a-1---d8754z-;rport=31488.
> Record-Route:<sip:REG_PROXY_IP:5166;lr;nat=yes>.
> Record-Route:<sip:LB_IP:5678;lr=on>.
> Contact:<sip:UAC_B at UAC_B_PRIV_IP:31468;rinstance=06b43c2b0e1ae81a>.
> To: "UAC_B"<sip:UAC_B at test.com>;tag=d6775b48.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 INVITE.
> Session-Expires: 95;refresher=uas.
> Min-SE: 90.
> Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE,
> SUBSCRIBE, INFO.
> Content-Type: application/sdp.
> Supported: timer.
> User-Agent: X-Lite release 1100l stamp 47546.
> Content-Length: 364.
> .
> #
> U +0.008000 REG_PROXY_IP:5166 ->  LB_IP:5678
> SIP/2.0 200 OK.
> Via: SIP/2.0/UDP LB_IP:5678;branch=z9hG4bK3ae9.a8d68282.0.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;received=UACs_PUB_IP;branch=z9hG4bK-d8754z-a9127351d94a483a-1---d8754z-;rport=31488.
> Record-Route:<sip:REG_PROXY_IP:5166;lr;nat=yes>.
> Record-Route:<sip:LB_IP:5678;lr=on>.
> Contact:<sip:UAC_B at LB_IP:5678;rinstance=06b43c2b0e1ae81a>.
> To: "UAC_B"<sip:UAC_B at test.com>;tag=d6775b48.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 INVITE.
> Session-Expires: 95;refresher=uas.
> Min-SE: 90.
> Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE,
> SUBSCRIBE, INFO.
> Content-Type: application/sdp.
> Supported: timer.
> User-Agent: X-Lite release 1100l stamp 47546.
> Content-Length: 381.
> .
>
> #
> U +0.000000 LB_IP:5678 ->  UAC_A_PUB_IP:31488
> SIP/2.0 200 OK.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;received=UACs_PUB_IP;branch=z9hG4bK-d8754z-a9127351d94a483a-1---d8754z-;rport=31488.
> Record-Route:<sip:REG_PROXY_IP:5166;lr;nat=yes>.
> Record-Route:<sip:LB_IP:5678;lr=on>.
> Contact:<sip:UAC_B at LB_IP:5678;rinstance=06b43c2b0e1ae81a>.
> To: "UAC_B"<sip:UAC_B at test.com>;tag=d6775b48.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 INVITE.
> Session-Expires: 95;refresher=uas.
> Min-SE: 90.
> Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE,
> SUBSCRIBE, INFO.
> Content-Type: application/sdp.
> Supported: timer.
> User-Agent: X-Lite release 1100l stamp 47546.
> Content-Length: 381.
> .
>
> #
> U +0.144000 UAC_A_PUB_IP:31488 ->  LB_IP:5678
> ACK sip:UAC_B at LB_IP:5678;rinstance=06b43c2b0e1ae81a SIP/2.0.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;branch=z9hG4bK-d8754z-5f2152497c1dcb39-1---d8754z-;rport.
> Max-Forwards: 70.
> Route:<sip:LB_IP:5678;lr>.
> Route:<sip:REG_PROXY_IP:5166;lr;nat=yes>.
> Contact:<sip:UAC_A at UAC_A_PRIV_IP:31488>.
> To: "UAC_B"<sip:UAC_B at test.com>;tag=d6775b48.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 ACK.
> Proxy-Authorization: Digest
> username="UAC_A",realm="test.com",nonce="4b9a102f000000030feed796808fa4eb1df2de3c9a2b1034",uri="sip:UAC_B at test.com",response="2f023b974dd4cde6f29387681168de8f",algorithm=MD5.
> User-Agent: X-Lite release 1100l stamp 47546.
> Content-Length: 0.
> .
>
> #
> U +0.000000 LB_IP:5678 ->  REG_PROXY_IP:5166
> ACK sip:REG_PROXY_IP:5166;lr;nat=yes SIP/2.0.
> Via: SIP/2.0/UDP LB_IP:5678;branch=z9hG4bK3ae9.a8d68282.2.
> Via: SIP/2.0/UDP
> LB_IP:5678;rport=5678;received=LB_IP;branch=z9hG4bK3ae9.a8d68282.2.
> Via: SIP/2.0/UDP
> UAC_A_PRIV_IP:31488;received=UACs_PUB_IP;branch=z9hG4bK-d8754z-5f2152497c1dcb39-1---d8754z-;rport=31488.
> Max-Forwards: 68.
> Contact:<sip:UAC_A at UAC_A_PUB_IP:31488>.
> To: "UAC_B"<sip:UAC_B at test.com>;tag=d6775b48.
> From: "UAC_A"<sip:UAC_A at test.com>;tag=406aba65.
> Call-ID: YjEyNjJhYzczOTIyYWYyMjkwZGZiOTFmMjdkNmNmODk..
> CSeq: 2 ACK.
> Proxy-Authorization: Digest
> username="UAC_A",realm="test.com",nonce="4b9a102f000000030feed796808fa4eb1df2de3c9a2b1034",uri="sip:UAC_B at test.com",response="2f023b974dd4cde6f29387681168de8f",algorithm=MD5.
> User-Agent: X-Lite release 1100l stamp 47546.
> Content-Length: 0.
> P-hint: rr-enforced.
> P-hint: rr-enforced.
> .
>
> On Fri, Mar 12, 2010 at 11:04 AM, Iñaki Baz Castillo<ibc at aliax.net>  wrote:
>    
>> 2010/3/12 Pavel Miskov<miskov.pavel at gmail.com>:
>>      
>>> Hello list,
>>>
>>> let me first show my scenario:
>>>
>>> UAC_A  --->  LB --->  |
>>>                     | PROXY+REG #1
>>>                     |      or
>>>                     | PROXY+REG #2
>>> UAC_B<--- LB<--- |
>>>
>>>        
>> Could you please repeat the trace but in a easier format:
>>
>>    ngrep -d eth0 -W byline -T port 5060
>>
>>
>>
>> --
>> Iñaki Baz Castillo
>> <ibc at aliax.net>
>>
>>      
> _______________________________________________
> Kamailio (OpenSER) - Users mailing list
> Users at lists.kamailio.org
> http://lists.kamailio.org/cgi-bin/mailman/listinfo/users
> http://lists.openser-project.org/cgi-bin/mailman/listinfo/users
>
>    

-- 
Daniel-Constantin Mierla
Kamailio SIP Router Masterclass, Berlin, March 22-26, 2010
* http://www.asipto.com/index.php/sip-router-masterclass/

More information about the Users mailing list