CellularContext and AT commands

I am working with BG96 cellular modem for cloud using tcp socket and it is working fine. For this i have used CellularContext::get_default_instance().
Now i want use another feature of modem like ftp or ntp using modem’s stack or in other words i want to send some AT command directly to modem and also want to continue above tcp activity.
If possible please give some suggestion how to do this.