Sipp caller and callee scenarios not functioning

Question

Assuming that the register is functioning correctly, can anyone find errors in the syntax of the following scenarios, it doesn't seem to work. I wanted to establish communication, but the caller dropped with a forbidden 180,

• Scenario: I'm attempting to establish a SIP communication link. The setup appears to be configured correctly, and there are no evident issues with the network connectivity or the register itself.

• Issue Encountered: During the process, when I expect a typical SIP response (like a 100 Trying or 180 Ringing), the caller is dropped. Instead of a standard response, I'm receiving a "forbidden 180" message. This response is unusual and not part of the standard SIP response codes, as far as I'm aware.

• Troubleshooting Attempts: I've checked the basic syntax of the SIP messages and the configuration of the register. All standard diagnostics suggest that the system should be functioning as intended. However, the issue persists, which leads me to suspect that there might be an overlooked error in the syntax or a deeper issue within the register's operation.

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE scenario SYSTEM "sipp.dtd">

<scenario name="Callee Scenario">

    <!-- Wait for an INVITE request from the caller and capture Record-Route -->
    <recv request="INVITE" crlf="true">
        <action>
            <ereg regexp="Record-Route: (.*)" search_in="hdr" header="Record-Route" assign_to="record_route"/>
        </action>
    </recv>

    <!-- Send 100 Trying to acknowledge the INVITE -->
    <send>
    <![CDATA[
      SIP/2.0 100 Trying
      [last_Via]
      [last_From]
      [last_To]
      [last_Call-ID]
      [last_CSeq]
      Contact: <sip:10.202.0.61:5063>
      Content-Length: 0

    ]]>
  </send>

    <!-- Send 180 Ringing to indicate the call is being alerted -->
    <send>
    <![CDATA[
      SIP/2.0 180 Ringing
      [last_Via]
      [last_From]
      [last_To];tag=[pid]SIPpTag01[call_number]
      [last_Call-ID]
      [last_CSeq]
      Contact: <sip:10.202.0.61:5063>
      Content-Length: 0

    ]]>
  </send>

    <!-- Optionally, pause for a moment to simulate ring time -->
    <!--<pause milliseconds="1000" /> -->

    <!-- Send 200 OK to accept the call -->
    <send>
    <![CDATA[
      SIP/2.0 200 OK
      [$record_route]
      [last_Via]
      [last_From]
      [last_To];tag=[pid]SIPpTag01[call_number]
      [last_Call-ID]
      [last_CSeq]
      Contact: <sip:10.202.0.61:5063>
      Content-Type: application/sdp
      Content-Length: [len]

      v=0
      o=user2 53655765 2353687637 IN IP4 10.203.0.11
      s=-
      c=IN IP4 10.203.0.11
      t=0 0
      m=audio 20000 RTP/AVP 0
      a=rtpmap:0 PCMU/8000
    ]]>
  </send>

    <!-- Wait for ACK from the caller -->
    <recv request="ACK"></recv>

</scenario>

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE scenario SYSTEM "sipp.dtd">

<scenario name="Caller Scenario">
  <!-- User1 sends an INVITE -->
  <send>
    <![CDATA[
      INVITE sip:[email protected] SIP/2.0
      Via: SIP/2.0/UDP 10.202.0.61:5062;branch=[branch]
      From: "User1" <sip:[email protected]>;tag=[call_number]
      To: <sip:[email protected]>
      Call-ID: [call_id]
      CSeq: 1 INVITE
      Contact: <sip:[email protected]:5062>
      Max-Forwards: 70
      Subject: SIPp Test Call
      Content-Type: application/sdp
      Content-Length: [len]

      v=0
      o=user1 53655765 2353687637 IN IP4 10.203.0.11
      s=-
      c=IN IP4 10.203.0.11
      t=0 0
      m=audio 20000 RTP/AVP 0
      a=rtpmap:0 PCMU/8000

    ]]>
  </send>

  <!-- Receive Trying, Ringing, and OK -->
  <recv response="100" optional="true"></recv>
  <recv response="180"></recv>
  <recv response="200" rrs="true"></recv>

  <!-- Send ACK -->
  <send>
    <![CDATA[
      ACK [next_url] SIP/2.0
      [routes]
      Via: SIP/2.0/UDP 10.202.0.61:5062;branch=[branch]
      From: "User1" <sip:[email protected]>;tag=[call_number]
      [last_To]
      Call-ID: [call_id]
      CSeq: 1 ACK
      Contact: <sip:[email protected]:5062>
      Max-Forwards: 70
      Content-Length: [len]

    ]]>
  </send>
</scenario>