I've found this below for you.
These messages occur if the PDV buffer size is configured incorrectly.
Try increasing or decreasing the value for port (x)
Found on CSE1K X21 3.00
Use the command PRT PDV <port#> in LD 117 to display both the current size of the PDV buffer and the number of PDV underflows.
Then use the command CHG PDV <port#> <delay> to change the PDV buffer size.
The <delay> parameter can take values from 0.5 ms to 8 ms.
This value should be initially tested at the default setting.
Increase the <delay> parameter value by 0.5 ms increments if an unacceptable level of voice quality is experienced (“pops and clicks”).
Decrease this value if an echo is experienced.
The goal is to operate with the smallest buffer possible.
Also this note was found below.
make the clock track of Media gateway 1 on Succession 3.0
Symptom:
Warning: PDV buffer for port# 3 may need to be changed
Too many Overflows: 1.
Errors pop up throughout day, during low traffic and high traffic period.
Cause:
SSCK 0 shows clocking state to be locking not locked.
ld 60
DTI000
.ssck 0
DSBL
IP DB PORT 1 Locking
IP DB PORT 2 DSBL
IP DB PORT 3 DSBL
IP DB PORT 4 DSBL
CALL SERVER CLK SRC: CC
Fix:
1) Run the trck pll1 command to make the clock track of Media gateway 1.
2) Make call that uses TDM resource in MG1.
This will ensure clocking stays in locked state.
In this particular case, site had clock controller in MG1 and MG3. During system bootup it will would check MG1 first for clock then MG3.
Finally this was spotted (which I think may be your actual problem!)
Getting PDV buffer warning.
Warning: PDV buffer for port# 3 may need to be changed
Too many Overflows: 1.
Altered PDV value on port 3 from 1.0msec to 7.0msec but no change.
Changed IP daughter board, but that had no effect on the issue.
PDV warning message has shifted to port 1.
Warning: PDV buffer for port# 1 may need to be changed
% Too many Overflows: 1.
Replace
SSC card on
main cabinet
All the best
Firebird Scrambler
Meridian Programmer in the UK
If it's working, then leave it alone!.