ta908e fxs high delay on quality stats

[edgonix]

What can cause that ta908e fxs interface have a high delay on quality stats,  I try to send faxes and they dont want to pass more than a page.

         Start                                        Out of                   Discard     Delay

ID       Time     From       To         Length Codec  Order    Pkts*  Avg   Max

--------------------------------------------------------------------------------

2946     4:38 PM  7875447557 7879220972 0:27   G711u  0       0       90    90