VTScada should work with any standard voice modem. Though we cannot guarantee the compatibility of third-party modems across all Windows operating systems, our engineers have provided the following comments on modems that they have used or have been used by our customers. We have no relationship with these manufacturers. **Note that fewer legitimate manufacturers are offering physical modems.** There will likely be none in the near future. For voice alarm notifications, we suggest using [Twilio](http://www.twilio.com/). - **US Robotics 5637** – The voice quality is good however they sometimes miss a user’s keypress on the phone. For this reason in 2020 we added a solution that gives audible feedback on each keypress so users can press the key again if it was missed. - **MultiTech MT9234MU-CDC-XR** – Built for industrial applications, this modem has high voice quality and DTMF detection is consistent. Ensure model number does not contain ‘NV’ (no voice). **This device has been discontinued but may still be available second hand from sites like eBay.** - **Zoom V.92 56K USB Mini External Modem - Model 3095** Tests in February 2020 indicated this device works with the current Windows 10 driver from the ZOOM website. http://www.zoomtel.com/products/dial_up_external_usb.html **This device has been discontinued but may still be available second hand from sites like eBay.** - **StarTech - USB 2.0 Fax Modem** - 56K External Hardware Dial Up V.92 Modem/Dongle/Adapter - Computer/Laptop Fax Modem - USB to Telephone Jack USB Data Modem - Network Fax/ Voice/CMR/POS https://www.startech.com/en-ca/networking-io/usb56kemh2 For more information, see the VTScada help file entitled, "Modem Configuration and Use."