Since the fax mode check box is now missing for the Telo it may mean that fax mode is now automatic for the Telo also.
I have not seen an announcement that that is the case however.
Fax mode only applies to incoming faxes.
Both the hub and the Telo require the *99 prefix to enter fax mode for sending a fax.
Fax mode disables echo cancellation so it usually isn't suitable for voice calls.
Telo with 2 Handsets, a Linx, and a Safety Phone
Telo2 with 2 Handsets and a Linx