Not able to send sms by AT+CMGS="mobile no"

Hi ,i am using EG91 module there i tried to send sms by below command but getting 350 error after pressing Ctl+Z

AT+CMGF=1

AT+CSCS=“GSM”

AT+CSCA?

AT+CSCA="+some no",145

AT+CMGS=“mobile no”

hi
ctl+Z
error 350

Dear Customer,

It’s not recommend to change the SMSC number unless you pretty sure the correct SMSC number.

Error 350 is usually due to:
- network only allow SMS over ims, but device is not registered IMS server. For example, Verizon network.
- Set the wrong SMSC number.
- Destination NO. is incorrect or not in whitelist

Best Regards,

How do we register a modem such as the EM12-G as an IMS server so that SMS can be sent with a Verizon SIM?