We built the controls and SCADA system for one of our customer’s new manufacturing plant. Part of it involves Ignition and one of its uses is for remote alarm notifications since they wanted email and SMS notifications for various alarms and events. They already have a SMTP server that we are using for the emails, but for the SMS messages, they did not want to purchase a modem for cost and security reasons, so we went with Twilio. The volume of messages is pretty low (400-500 per month on average), compared to most uses of Twilio, and is well below the threshold of being invoiced every month. The plant manager at the time did not mind manually charging the Twilio account periodically, however the new plant manager hates this and wants to move to something else. I did a decent amount of research on this, including this thread (Cellular Modems for SMS Notifications), but I haven’t gotten the answer that the plant manager probably wants to hear.
So, to confirm is there any alternative to Twilio that works with Ignition and invoices monthly despite low message volume? And if there is no alternative, realistically, how long term viable is using a modem?