Because a SIP trunk is not a physical connection, there is no explicit limit on the number of calls that can be carried over a single trunk.
因为一个SIP中继不是物理连接，也没有就可以在一个单一的电话号码进行明确的主干限制。
2
Within a switching system, a connection or circuit between inlets and outlets of the same or different switching networks. An intraoffice trunk.
在交换系统中，同一或不同交换网络的引入线和引出线之间的连接部分或电路。又称局内中继线。
3
SIP Trunk is a logical connection between an IP PBX and a Service Provider's application servers that allows voice over IP traffic to be exchanged between the two.