Voice modem users,

Microsoft has broken TAPI with Windows 10 1903.

If you update workstations to this Windows version, you will struggle to get any voice functions from your voice modems, especially with the Multi-Tech USB modems.

We installed the update here and tested against the Multitech modem. We did have to re-install VTScada and also tweak the modem registry setting to add back in the Network Service user. The registry key is at -

Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class{4d36e96d-e325-11ce-bfc1-08002be10318}

But, it did work. If it turns pout to be a bigger issue, we will keep it updated here.

Remember, we don't handle the modem or voice in the same manner as WIN911. So a problem or a even a fix for them, may not have the same impact on us.

But it is nice to get a heads up like this so we can get ahead of it. Thank you!

If you tire from managing modems and have an internet connection to your SCADA server, note that you can always use Twilio for voice and SMS alarms.

As an additional note here, I just had a customer computer that had this update applied today. They had already installed important bios updates from dell as well (which would be another useful step), and I was able to get the modem working again by following this process (and no reinstall was required):

1. Go into Control Panel and open 'Phone and Modem', and go to the Advanced tab

2. Select the Trihedral entry and remove it
   

3. Go into the registry key Doug mentioned previously and open the permissions on it

4. Add NETWORK SERVICE with Full Control

5. Go back into 'Phone and Modem' and add the Trihedral entry back in on the Advanced tab
6. In your VTScada application, open the properties for that modem tag and add a character to the end of the line name (any character, this is just used to track which modems share a phone line) and select 'OK' to save that change
7. If desired, go back and delete the extra character from the line name. Either way, everything should be working again
8. If you're nervous about making changes in the registry, reinstalling VTScada is another option that will do all of this for you (it just requires stopping VTScada and your application shortly while you run the installer)

Thanks for the update, Jennifer.

We were/are able to get modems to work on Windows 10 1903 installations that are fresh

However we had one specific hardware config with Intel hardware that also didn't support 1903 which we were unable to get to cooperate even after trying all this and had to restore an image to 1809.

Dave, Twilio is great where we can use it, but it's a "no-go" from 90% of clients. And it doesn't work when the Internet is down or you forget to pay the bill. Are there any plans for VTScada to support SIP devices directly to a phone line so we don't need Twilio?