Through CTC devices

To add a signaling path defined through CTCs, the device must be unallocated before you issue the SETXCF START command.

When you add an outbound path on the sending system, also add its associated inbound path on the receiving system.

To ensure that the device is not allocated, issue:
```
  DISPLAY  U,CTC,ALLOC
```
To add an inbound or outbound signaling path, issue:
```
  SETXCF  START,PATHIN,DEVICE=indevnum
  SETXCF  START,PATHOUT,DEVICE=outdevnum
```
Use the MAXMSG, RETRY, and CLASS keywords as needed.