If you have configured in Asterisk (or you fron-end FreePBX) sip trunk provider of VoIP, but outbound link is not working, and in output:# asterisk -rx "sip show peers"you see that your sip trunk UNREACHABLE in the

使用 telnet 测试现有监听端口连通性 可以使用 Linux 自带的 telnet 工具来测试现有端口的连通性，测试命令为： telnet <host> <port># host 是目标服务器 IP，port是待测试端口号示例： 可以如下指令测试 22 端口的连通性： telnet 127.