Ask yourself what happens if gateway phone has connection issues or it just freezes. These applications depend on cellphone, e.g. they cannot handle big amount of messages and have 30 seconds timeout.
In Wialon you can connect SMPP account with local number that allows to use local prices for messages. User tariff cannot be cheaper than bulk SMS price from SMPP provider.
If you need live SIM card - this is also possible. You will need Linux host with hardware modem (COM or USB) connected to the internet, we can install special software that will send all SMS alerts from your service via modem with local SIM number. SMPP service or remote physical modem is much more reliable and professional solution than relying on user devices. They are too slow to deliver big amount of SMS. Industrial modem or SMPP provider can handle hundreds and thousands SMS per minute. I doubt that cell phone can handle the same load 24/7.
WDC Administrator
Gurtam