What is the baud rate for a HP 2140 Fax machine?

SOURCE: baud rate

1. Why 9600?

Because you are using a VOIP service it can from time to time lose connection briefly. The slower the speed the less data can be loss do to network congestion. It also gives the error correcting function of the receiving fax a better chance of filling in any lost data.
9600 is a good choice becasue the industry minimum is 9600. This means you will be able to communicate pretty much any fax thats is still tickin today. Raising the speed will get you a faster transfer but will also increase the chance that you are sending data at a faster rate than the recieving fax can send.

2. How to change the baud rate....

Press Menu/Set, 2, 0, 1.
Press ▲ or ▼ to select Basic or
Normal (or High*).
Press Menu/Set.
Press Stop/Exit.
* High is available for FAX-2910, FAX-2920
and MFC-7225 only.
Note
Basic reduces the modem speed to 9600
bps. Unless interference is a recurring
problem on your phone line, you may
prefer to use it only when needed.
Normal sets the modem speed at
14400 bps.
High sets the modem speed at
33600 bps.

SOURCE: Change baud rate on panafax uf880,885

That won't make any difference. ALL fax machines are ANALOG and won't work on a DIGITAL phone lines reliably

SOURCE: how to change baud rate on fax machine panasonic

press menu#9000* for tx rate press 717 then value 1,2,3,4,5,for rcv 718 then value

SOURCE: How can I set up

Use the fax setup wizard from the HP toolbox , when it asks if you have an answering machine connected to the fax line say yes. Or setup a distinctive ring from you phone company and set the fax machine to answer double rings only. Use fax setup wizard to do this as well.

SOURCE: I need fax setup for Hp 2140 Fax or a manual

http://static.highspeedbackbone.net/pdf/HP-2140-FAX-Machine-Manual.pdf