被叫未接通 原因为 requested circuit/channel not available

一般是SD或TCH拥塞的原因,具体要根据流程和消息查看!

If an idle traffic channel is not available at the assignment instant, the network may place the traffic channel request in a queue. Calls arriving when all positions in the queue are occupied shall be cleared by the network using the cause #34 "no circuit/channel available".
The maximum queuing interval is supervised by the network. The limit is a network dependent choice. In case the network is not able to allocate a traffic channel within the queuing limit, the network will release the call using cause
#34 "no circuit/channel available".
可能是用户排队的较多，无可用的资源了，可以通过扩容的方式等解决，或者换个时间段，等用户少些的时候拨打电话

拥塞了。。。或者是申请的信道不可用，，，，看看是不是设备问题或者是偶发事件

申请链路不可用，一般就是考虑拥塞，比如业务量太高，或者载频故障导致的容量降低等原因。