FXO lines Hong Kong

Hello everyone,

I’m working in Hong-Kong, and I’m setting up an asteriskNOW server with a Grandstream GXW 4108 and many ip phones. I’ve got some troubles configuring my GXW gateway with the analog lines. Thus, the phone calls I make are pretty hazardous and of poor quality.

Can anyone help me with the HK analog lines network characteristics? And what should I put in my Gateway config page in order to have the perfect set up? Thanks!