IA apn用于LTE attach。
手机检测到sim卡后,便会加载这个attach apn. 不过很多运营商并没有严格规定attach apn,所以常常使用default类型的apn。
-
IA Attach Spec
Spec 24.301 4.1
The NAS for EPS follows the protocol architecture model for layer 3 as described in 3GPP TS 24.007 [12]; however,due to the objective of EPS to provide the subscriber with a "ready-to-use" IP connectivity and an "always-on" experience,the protocol supports a linkage between mobility management and session management procedures during the attach procedure(see subclause 4.2)
Spec 24.301 4.2
During the EPS attach procedure, the network can activate a default EPS bearer context (i.e. if the UE requests PDN connectivity in the attach request). Additionally, the network can activate one or several dedicated EPS bearer contexts in parallel for PDN connections of IP or Ethernet PDN type. To this purpose the EPS session management message