InviteRequestProcessor类中，channelid从invite消息的header subject获取，不再从第一行request line获取。原因是和第三方平台对接时，发送的invite消息第一行为国标平台编码而不是设备通道编码，导致报错通道不存在，返回404。

src/main/java/com/genersoft/iot/vmp/gb28181/utils/SipUtils.java

@@ -2,8 +2,10 @@ package com.genersoft.iot.vmp.gb28181.utils;
 
 import gov.nist.javax.sip.address.AddressImpl;
 import gov.nist.javax.sip.address.SipUri;
+import gov.nist.javax.sip.header.Subject;
 
 import javax.sip.header.FromHeader;
+import javax.sip.header.Header;
 import javax.sip.message.Request;
 
 /**
@@ -18,6 +20,13 @@ public class SipUtils {
         FromHeader fromHeader = (FromHeader)request.getHeader(FromHeader.NAME);
         return getUserIdFromFromHeader(fromHeader);
     }
+    /**
+     * 从subject读取channelId
+     * */
+    public static String getChannelIdFromHeader(Request request) {
+        Header subject = request.getHeader("subject");
+        return ((Subject) subject).getSubject().split(":")[0];
+    }
 
     public static String getUserIdFromFromHeader(FromHeader fromHeader) {
         AddressImpl address = (AddressImpl)fromHeader.getAddress();