default or selected kernelversion does not have config value CONFIG_CXT1E1.
Result is shown for kernelversion 6.5.1

SBE wanPMC-C[421]E1T1 hardware support

modulename: cxt1e1.ko

configname: CONFIG_CXT1E1

Linux Kernel Configuration
└─>Device Drivers
└─>Staging drivers
└─>SBE wanPMC-C[421]E1T1 hardware support
In linux kernel since version 2.6.35 (release Date: 2010-08-01)  
This driver supports the SBE wanPMC-CxT1E1 1, 2 and 4 port T3
channelized stream WAN adapter card which contains a HDLC/Transparent
mode controller.

If you want to compile this driver as a module say M here.
The module will be called 'cxt1e1'.

If unsure, say N.

source code: