Problem with fax (commercial)

I have problem with ReceiveFAX - if my asterisk works for 3-4 days, there is problem with ReceiveFAX - call is answered, there is a fax negotiation tone, but the fax isnt received. In log there is information “res_fax_digium.c: Huh? Failed to open FAX session ‘XXX’”. After asterisk restart fax works fine for next 3-4 days.

What could be a problem?

If by “(commercial)” you mean you are using the Digium fax software with a paid for licence from Digium,these forums are not a place through which to contact Digium for commercial support. You need to go to the support section on their website. Although some Digium people can be found here, they are not here in any official capacity.

The reason there is a sub-forum for the free licence is that Digium don’t provide support for that; it is not because commercial support is provided on another of the forums.