PLS8-E: LTE connection only after 12 minutes, AT^SIND: ltebot, AT+CEMODE | Telit Cinterion IoT Developer Community
March 29, 2022 - 5:48pm, 558 views
Hi, one of our customers uses a private APN and complained that with our PLS8-E based solution he can only use 2G, despite using LTE with other devices.
I found that SMONI will initially tell "4G... LIMSRV", but after a few seconds degrade to "2G... --" and then "2G... NOCONN". In this state, we can open a PPP connection with AT+CGDATA="PPP"...
Exactly 12 minutes after that has been established, we receive a +CIEV: psinfo,17 and the connection "upgrades" to 4G.
Now I noticed that 12 minutes is the same as the LTE Backoff Timer, and sure enough,
> ^SIND: ltebot,0,1,26,"apn.ourValuedCustomer.com","Insufficient resources"
How can I avoid this?
I was looking into AT+CEMODE, because I thought that it might be related to our default CEMODE of 1, which in the manual says
> "If it is unable to obtain voice service in the LTE network ... it shall disable the LTE capability, which results in re-selecting 2G or 3G".
I tried to set AT+CEMODE=2 for data-centric service that does not do this, but I invariably get a "CME ERROR 4: Operation not supported" from that command.