SGs 接口的短信寻呼。

wenliu

规范中对短信寻呼定义：

If the Service indicator information element in the SGsAP-PAGING-REQUEST message indicates "SMS indicator", the MME shall handle the paging request as follows:
a)        If the UE is known:
-        if the UE is considered to be IMSI attached for EPS and non-EPS services or IMSI attached for EPS services and "SMS only", the MME shall page the UE based on the location information stored in the MME. If the SGsAP-PAGING-REQUEST message does not include the Location area identifier information element, the MME may set the "VLR-Reliable" MM context variable to "false"; or
NOTE 2:        If location area identifier information element is included in the SGsAP-PAGING-REQUEST, it is not used in paging the UE.

因为短信不需要CSFB。。。当UE进行寻呼响应之后，MME会把TAI+ECGI返回给MSCS的，MSCS会把这个信息写到话单里的。。。。