Questions[dialup](server)

I have dial-up server and client software that I want to be able to test and script. Unfortunately, I don't own a landline. Much less, multiple lines that I can use to test concurrent connections.

What I do have, is a handful of modems and a computer to plug them into. Is there any way that I could simulate a phone line in such a way? As in, actually be able to plug in a landline telephone in, get a dial tone, be able to dial a number, and route it to my software on the server?

I appologize if this is not the appropriate forum for this question. I'm afraid I have no idea where to start with this, or if what I'm attempting is entirely half-baked.

We are using Linux + KVM + Qemu with libvirt on our servers to manage virtual WIndows 2008 Servers. The Host is Ubuntu 11.04.

The point is on one of our Windows server 2008 guest, we need to connect a dial-up modem. After connecting the modem to the Host, we found that it was connected to /dev/ttyS0. We did checked that the modem was recognized using

echo atdt3333333 > /dev/ttyS1

Server .xml configuration contains

<serial type='pty'>
  <target port='0'/>
</serial>
<serial type='dev'>
  <source path='/dev/ttyS0'/>
  <target port='1'/>
</serial>
<console type='pty'>
  <target type='serial' port='0'/>
</console>

Now, launching our virtual server, Windows doesn't see any COM port at all, and therefore doesn't see the modem ( all sort of virsh define / stop / start ... had been done )

Does anyone know how to achieve this ?

there's a computer ("server") that has no Internet connection, and it is located in a place with no GSM signal. The only way to get connection to it is an analog modem (US Robotics 56Kbit/s). This modem is connected to a national PSTN line with a geographical number, and the server (running a modern Linux distribution) is configured to offer a dial-in serial terminal. To clarify, when you phone to this PSTN line, the modem handshakes (I think it's the V90 protocol), then you're presented with the login and then you are in on ttyS0. There's no IP/PPP protocol stack, just the serial terminal.

I would like to connect to this server in any way that does not require me to carry around a physical analog modem and (what's worse) finding around a physical PSTN line which is really a scarce resource at least in business context here in Italy. To clarify: the PSTN line on the server side is the only way through, but I would like to be able to connect to it without a physical PSTN line on the client side.

Some ideas that came through my mind but I do not know if they can be really implemented or not:

• Having a mobile phone connected through bluetooth/USB. Old phones exported a ttyUSB that handled AT commands, but then there was no way (AFAICT) to get the audio stream. I don't know if it's technically possible to write an Android app that makes a phone call, then encodes the audio into a semi-raw UDP stream.

• Routing the call through VOIP. Googling around, some people seems to have had mixed success with doing analog modem calls through a VOIP termination with g711 (uLaw/aLaw). It looks like it is possible to get at least 9600bps, which is enough for me.

• Even if one of the above is possible, is there any software available that emulates the full V90 protocol/handshake/whatever and en/decodes audio into bytes?

• Is there any online service that offers a battery of analog modems to subscribers? Doesn't sound a business I would personally invest on, but you never know :)

• Is there any physical object that is the modern UMTS equivalent of an analog modem, like a box connected through USB where you put the SIM inside, it does all the magic, and gives you a ttyUSB on your PC?

• Assuming that I can physically access the server just once, is there anything I can install (either hardware or software) on the server and that would make my life easier? The only requisite is that must go through a standard national PSTN line (dual twisted copper), there's no other way to get any other signal. The modem looked like the best option, at first, but you never know.

Thanks!

I'm in charge of managing an array of Windows Embedded 7 Standard based PCs (they act just like plain old Windows 7).

The computers have 3G cards as their only means of communication, and are on buses. Right now, the 3G cards are configured in NDIS mode which in theory will maintain the connection automatically and persistently. However, sometimes the 3G link fails and never comes back up.

Can someone help me out here? My basic requirements are

• Internet is available always
• If the connection fails, it is detected and retried

Is RAS/DUN more reliable for this sort of thing than NDIS?

We have some physical servers that we cannot virtualise because they are connected to analog modems for alert paging.

We need to retain this functionality, but virtualise the servers and reduce the pile of individual modems down to something that can be rackmounted in a minimal number of U.

So I guess I'm seeking a stack something like this:

• Rackmount bank of 8-16 modems
• Network connectivity from the modem bank onto the network
• Some kind of client software on the VMs that allow them to create a modem COM port, via the IP connection

I'm already familiar with a partial solution - MOXA make an IP-connected serial server that can connect to a bunch of modems. This works in exactly the manner we need, but it doesn't go as far as integrating the modems - So we still have a bunch of them sat on rack shelves.

Can anyone point me in the right direction on this?

Edit: I'm thinking I can probably get closest to what I'm after by stacking one of these with one of these. I was hoping there would be an integrated, single-unit solution but maybe not.