JAIN-SIP（Java API for Integrated Networks - Session Initiation Protocol）是用于实现SIP（Session Initiation Protocol）的Java API。以下是使用JAIN-SIP库编写一个简单的SIP服务器的基本步骤：

1.添加JAIN-SIP库依赖项：

首先，确保在项目中包含JAIN-SIP库。你可以从官方网站或者使用Maven或Gradle等构建工具获取库。

如果使用Maven，可以在pom.xml文件中添加以下依赖项：

<dependency><groupId>javax.sip</groupId><artifactId>jain-sip-api</artifactId><version>1.2</version> <!-- 使用最新版本 -->
</dependency>

如果使用Gradle，可以在build.gradle文件中添加以下依赖项：

implementation 'javax.sip:jain-sip-api:1.2' // 使用最新版本

2.编写SIP服务器代码：

下面是一个简单的SIP服务器的示例代码，监听在本地IP地址和5060端口上：

import javax.sip.*;
import javax.sip.message.*;
import javax.sip.header.*;
import java.util.Properties;public class SimpleSipServer implements SipListener {private SipFactory sipFactory;private SipStack sipStack;private SipProvider sipProvider;public void init() throws PeerUnavailableException, TransportNotSupportedException, InvalidArgumentException, ObjectInUseException, TooManyListenersException {// Create and set the SIP stack propertiesProperties properties = new Properties();properties.setProperty("javax.sip.STACK_NAME", "simpleSipServer");properties.setProperty("javax.sip.IP_ADDRESS", "127.0.0.1");properties.setProperty("javax.sip.OUTBOUND_PROXY", "127.0.0.1:5060/UDP");properties.setProperty("gov.nist.javax.sip.TRACE_LEVEL", "32");properties.setProperty("gov.nist.javax.sip.DEBUG_LOG", "simpleSipServerDebug.txt");properties.setProperty("gov.nist.javax.sip.SERVER_LOG", "simpleSipServerLog.txt");// Create SIP stacksipFactory = SipFactory.getInstance();sipFactory.setPathName("gov.nist");sipStack = sipFactory.createSipStack(properties);// Create SIP providerListeningPoint listeningPoint = sipStack.createListeningPoint("127.0.0.1", 5060, "udp");sipProvider = sipStack.createSipProvider(listeningPoint);sipProvider.addSipListener(this);}public void processRequest(RequestEvent requestEvent) {// Handle incoming SIP requests hereRequest request = requestEvent.getRequest();// Add your logic to process the request}public void processResponse(ResponseEvent responseEvent) {// Handle incoming SIP responses hereResponse response = responseEvent.getResponse();// Add your logic to process the response}public void processTimeout(TimeoutEvent timeoutEvent) {// Handle SIP timeouts here}public void processIOException(IOExceptionEvent exceptionEvent) {// Handle SIP I/O exceptions here}public void processTransactionTerminated(TransactionTerminatedEvent transactionTerminatedEvent) {// Handle transaction termination here}public void processDialogTerminated(DialogTerminatedEvent dialogTerminatedEvent) {// Handle dialog termination here}public static void main(String[] args) {try {SimpleSipServer sipServer = new SimpleSipServer();sipServer.init();System.out.println("SIP Server is running...");// Wait forever (you can add your own logic here)while (true) {Thread.sleep(1000);}} catch (Exception e) {e.printStackTrace();}}
}

请注意，此示例中使用的IP地址和端口是本地的，你可能需要根据你的需求更改它们。