e1 link is fluctuating , what can be the issue

Router#sh int serial 0/3/0:0

Serial0/3/0:0 is down, line protocol is down

Hardware is GT96K Serial

Description: "Router"

Internet address is 10.100.1.58/30

MTU 1500 bytes, BW 1984 Kbit, DLY 20000 usec,

reliability 163/255, txload 1/255, rxload 1/255

Encapsulation PPP, LCP Closed, loopback not set

Keepalive set (10 sec)

Last input 00:00:48, output 00:00:38, output hang never

Last clearing of "show interface" counters 29w6d

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: weighted fair

Output queue: 0/1000/64/0 (size/max total/threshold/drops)

Conversations 0/5/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

Available Bandwidth 1488 kilobits/sec

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

5113915 packets input, 582233138 bytes, 0 no buffer

Received 0 broadcasts, 9 runts, 8904 giants, 0 throttles

1888935 input errors, 1888927 CRC, 1225559 frame, 110516 overrun, 0 ignored

, 507633 abort

7532290 packets output, 1034655047 bytes, 0 underruns

0 output errors, 0 collisions, 19 interface resets

0 output buffer failures, 0 output buffers swapped out

4321 carrier transitions

Timeslot(s) Used:1-31, SCC: 0, Transmitter delay is 0 flags