Why does SMS from the site take much longer than through the modem interface?

Question

ASP.NET

There is a website on ASP.NET, a megaphone modem is plugged into the server.
The site sends SMS using it via the COM port, made according to the recipe https://habr.com/post/256687/
And here's what's strange: the modem has its own software interface, if you send SMS through it, it arrives in less than a minute.
And if through the site, then SMS can go 5-10-15 minutes.
What is it connected with and can it be overcome?

Answer 1

You need to see how the sending is done on the site.
How do we know what kind of site you have and how the mailing list is configured on it. The site is just a UI, maybe it collects all SMS requests, saves them in a queue, and then sends them out every 5-10-15 minutes?

Answer 2

Well, experiment with the COM connection parameters. Open hyperterm (or whatever you have there) with the same parameters as in the ASP application, send a text message with AT commands, measure the speed, change the connection parameters.