HP 3380 Fax Machine

[baashaa69]

Hey guys i have a problem i have a HP 3380 all in one fax, copier etc etc on the bt broadband voice service and it loses around 20% of the fax's bt are invetsigating for me and they've been great trying to sort out the problem but we can't seem to fix it..

ANY IDEAS???

[mattpark]

Welcome to the forum.

You may or may not know, that by default faxing over VoIP should not work. end of. The reason for this is that fax works off an analogue signal, and VoIP is digital.

When you fax over VoIP it gets sent via analogue, converted in to digital, and then re-converted to analogue at the other end again. In most cases this causes small amounts of fax data loss... hence you having only part of the picture.

Now, people have got it to work reliably over VoIP using various encoding and codec methods, and pieces of kit.

Do you know what codec is used for BT broadband voice?

Matt

[baashaa69]

hi there

what is a codec i dont know what they are or what they could could you please explain further for me please

[mattpark]

Hi,

A codec is basically the "format" of the audio sent from point to point.

When you choose a codec, you make a trade off between bandwidth used and the quality of the audio.

For example:
G.711, a higher quality audio which takes up 64 Kbps.
G.729, a low quality audio which takes up 8 Kbps.

The commonest problem with sending a FAX over VoIP networks is the easiest to deal with. A low bit rate voice codec is unable to carry a fast modem signal without severe distortion. Would you really expect an 8kbps G.729 codec to convey a 9.6kbps FAX modem signal correctly?

At the end of the day, faxing over GSM codecs will always be unreliable - and i highly suspect BT uses one of these codecs.

There is now a protocol/codec standard designed for faxing. T.38 is an ITU standard for sending FAX across IP networks in a real-time mode. Drop a message over to BT asking if a) their netowork offers T.38, and b)if the hardware supplied will support it.

Hope this will help.

Matt