You can use SNMP. In this example we're grabbing the status of trunk group 50 member 1.
** FAIL: Trunk 50/1 01D04: (1.3.6.1.4.1.6889.2.73.8.1.26.3.1.5.50.1)
[Current: maint-NE/idle] Does not contain [in-service]
This is from IPSentry, but there are lots of tools out there. I only look for the first B channel of each PRI, in my experience when a PRI has trouble all the B channels are dead, haven't seen random B channels fail by themselves.
Regards,
....Mike