fax transmission from PC to plain fax machine problem

some times the transmission doesn't even start and other times it stops by the end of the first page!i also tried to send a 2-pages fax from my pc(line b) to the other line(a) where the fax machine is on and happens the same(no problem to other receivers until now). i tried to put a different fax machine(panasonic) in the same place(a) and it worked.the wierd thing is that when i tried to change the telephone line of the pc(b) with a third one(x) and send again... no problem!so i liked this "x" line but...when i tried to send from pc(b) to the fax machine(telcom) which i placed on the (x) line i got the same problem!the 2 lines (a) and (x) are by the new "hol" provider and the third line (b) is thankfully still on the old provider "ote".i suppose it could propably has to do something with my new provider and router(onaccess) because i have this problem since i installed it.i would really appreciate any kind of help since the technical department of the provider comes with nothing every time i bring the matter up.ps: !!! i was trying today again and it worked... so i called them to see what happened differently and before i say anything they told me that they face a general problem today with their servers... unfortunatelly their problem was solved but brought up mine again