Fax server dialing rule stop working

Hi all,

   Our shard fax server stop working for unknown reason. All fax will become Pending. However, if I enter the number manually(91xxxxxxx), the fax working as normal. If using the format(+1 (xxx) xxxxxxx) as usual, it goes to pending. It looks like dialing rule not apply anymore. I check the dialing rules, and they are still there. Anyone know how to fix it or what case it? Thank you very much.

We use 2008 R2 Standard, and USR USB fax modem.