实现一个拨打SIP Call的MCP服务器：技术详解与最佳实践
概述
模型上下文协议（MCP）是现代AI模型与外部资源交互的标准协议。本文将深入介绍如何实现一个功能完整的SIP呼叫MCP服务器，基于UDP协议实现高效的VoIP通信，并提供丰富的管理和监控功能。有了该mcp server，AI智能体可以主动发起电话呼叫到用户手机，或者用户通过手机打电话给AI智能体。
技术架构
核心组件
- MCP服务器核心：处理与AI模型的MCP协议通信
- UDP SIP客户端：基于UDP协议的SIP实现，提供更好的网络兼容性，webrtc协议的SIP正在开发中。
- 状态管理系统：实时监控SIP连接状态和通话质量
- 统计与日志系统：记录通话历史和性能指标
安装依赖
npm install @modelcontextprotocol/sdk
npm install dgram # Node.js内置UDP支持
npm install node-rtp # RTP协议处理
完整代码实现
由于第三方的sip.js包没有支持udp协议的sip，因此需要自己实现UDP协议的SIP接口
相关代码写在udp_sip.js文件中，如下：
import dgram from 'dgram';
import {
EventEmitter } from 'events';
import crypto from 'crypto';
/**
* 高性能UDP SIP客户端实现
* 支持SIP注册、呼叫、状态管理等功能
*/
export class UDPSIPClient extends EventEmitter {
constructor(config) {
super();
this.config = config;
this.socket = dgram.createSocket('udp4');
this.callbacks = new Map();
this.cseq = 1;
this.branchBase = 'z9hG4bK';
this.tagBase = Math.random().toString(36).substring(2, 15);
this.stats = {
messagesSent: 0,
messagesReceived: 0,
callsAttempted: 0,
callsCompleted: 0,
rtpPacketsSent: 0,
rtpPacketsReceived: 0,
registrationAttempts: 0,
registrationSuccesses: 0
};
this.localIP = '0.0.0.0';
this.actualLocalPort = 0;
this.registered = false;
this.currentCall = null;
this.setupSocket();
this.clientReady = this.initialize();
}
setupSocket() {
this.socket.on('message', (msg, rinfo) => {
this.stats.messagesReceived++;
this.handleMessage(msg.toString(), rinfo);
});
this.socket.on('error', (err) => {
this.emit('error', err);
});
this.socket.on('listening', () => {
const address = this.socket.address();
this.localIP = address.address;
this.actualLocalPort = address.port;
this.emit('ready');
});
}
async initialize() {
return new Promise((resolve, reject) => {
this.socket.bind(this.config.localPort, (err) => {
if (err) {
reject(err);
} else {
resolve();
}
});
});
}
generateBranch() {
return `${
this.branchBase}-${
crypto.randomBytes(8).toString('hex')}`;
}
generateCallId() {
return `${
crypto.randomBytes(16).toString('hex')}@${
this.localIP}`;
}
async sendRequest(method, uri, headers = {
}, body = '') {
const callId = this.generateCallId();
const branch = this.generateBranch();
const cseq = this.cseq++;
const baseHeaders = {
'Via': `SIP/2.0/UDP ${
this.localIP}:${
this.actualLocalPort};branch=${
branch};rport`,
'Max-Forwards': '70',
'From': `${
this.config.username}@${
this.config.server}>;tag=${
this.tagBase}` ,
'To': `${
this.config.username}@${
this.config.server}>` ,
'Call-ID': callId,
'CSeq': `${
cseq} ${
method}`,
'Contact': `${
this.config.username}@${
this.localIP}:${
this.actualLocalPort}>` ,
'User-Agent': 'SIP-MCP-Server/1.0',
...headers
};
let request = `${
method} ${
uri} SIP/2.0
`;
for (const [key, value] of Object.entries(baseHeaders)) {
request += `${
key}: ${
value}
`;
}
request += `Content-Length: ${
body.length}
${
body}`;
return new Promise((resolve, reject) => {
const timeout = setTimeout(() => {
this.callbacks.delete
