Layer 2 qo down, configure Asterisk with pri_persistent_laye

Asterisk Asterisk Support
1

Hi,
My Telco brings BRI layer 2 down when line is on idle. There is a configuration option pri_persistent_layer2_option.
How I can activate this option ?
Thank

2

I got libri 1.4 r2280 from svn and it is ok now