Re: [hylafax]: how to use in the enterprise

On Tuesday, 9 April 2019 14:28:41 BST Carsten wrote:
> Hello list,
> 
> what is the maximum amount of users (outbound caller/inbound receiver)
> on a hylafax+ server?

That depends how you are connecting to the Public Switched Telephone Network.  
An analogue telephone line supports only one call at a time.  If you are using 
ISDN then a Basic Rate Interface supports two calls; but most  telcos still 
offering ISDN now only support Primary Rate Interfaces.  A PRI supports 30 
calls.

If you are using a SIP trunk, then you can make about 27000 calls at one time  
(each call requires two UDP ports, one for each direction; there are 65536 of 
them, but all the 4-digit numbers and smaller are used for other things).  
Each call needs 16kbits/second  (decimal kilobits)  so this volume of calls 
will fit into a 500Mb/s network connection.

Accepting a FAX will also use up a port; two faxes coming in to Hylafax will 
reduce the number of concurrent calls by one.

> I have learned, that if you have an underlying ASTERISK server, You
> need one IAX Modem for each CallerID.
> Is this correct?

Yes; but IAXModem is a piece of Open Source software, not something you have 
to pay for!  You can run as many copies as you need.  A standard Linux kernel 
supports 32767 process table entries, which is more than enough; but you could 
compile a custom kernel to support a bigger process table.

> If so, I have also learned, that each IAX Modem needs a single tcp port.
> This would lead me to the conclusion, that the maximum amount of IAX
> Modem on one IP address would be limited by the free tcp ports. Correct?

IAXModem  is only going to eat a TCP port if it's running a different machine 
than Asterisk.  If both are on the same machine, Hylafax will talk to IAXmodem 
via a device file in /dev exactly as though it were a real modem.

> If those estimations are correct, would it be possible to extent the
> range of ports by using a second or third, a.s.o. IP adress bound on
> the ETH-adaptor?
> 
> Examble:
> TTYIAXA0001 = 10.10.10.1:10001
> TTYIAXA0002 = 10.10.10.1:10002
> ...
> TTYIAXA9999 = 10.10.10.1:19999
> TTYIAXB0001 = 10.10.10.2:10001
> ...
> TTYIAXB9999 = 10.10.10.2:19999
> TTYIAXC0001 = 10.10.10.3:10001
> ...
> a.s.o.

Sort of. You might have to use physically separate NICs as opposed to multiple 
addresses on the same interface.

But in spite of all the above, the processing of fax pixels into zeros and 
ones will take up some time; probably more time than sending them down the 
phone line  (especially if you are trying to use LibreOffice in headless mode to 
convert MS Word .docx files to faxes),  and this is what will end up setting 
the ultimate limit.

> Just to make clear: We are evaluating to replace some other FAX
> solution with HylaFax+ serving 100.000 user in total -no, I am not
> kidding!!
> Is hylafax capable of such size?

Yes -- it is the hardware, not the software, that sets the limits.  You might 
well have 100 000 users, but they are never all going to be faxing at the same 
time!  This is all standard contention ratio / diversity factor stuff.

> Additional: Is there any way to have "just" Hylafax+ installed, w/o
> the need of a PBX (e.g. Asterisk), if connections are a SIP Trunk?

You will need to be running Asterisk and modem emulation software just to get 
from Hylafax to the PSTN.

--
Julie Montoya
Busting stereotypes since 1971




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