Yes, similar to Nginx or Apache for HTTP there are programs like FreeSwitch or Asterisk that serve SIP+Media traffic for you. You still need a service that does routing to your server based on a phone number. This is called "SIP trunking", and many companies like Twilio, Vonage, Bandwidth, etc. offer it.
In some countries even phone carriers may offer SIP trunking for individuals. But most often they work with a handful of resellers, who in turn have smaller and smaller companies as their clients. So, if you only need to support a small volume of calls you'd find that your prices per connection or per minute are higher.
Similar to sending email, telephony is a business of volume. The more call you make the less your prices are going to be. I worked in telephony space for a few years, and it's a fascinating industry.
In some countries even phone carriers may offer SIP trunking for individuals. But most often they work with a handful of resellers, who in turn have smaller and smaller companies as their clients. So, if you only need to support a small volume of calls you'd find that your prices per connection or per minute are higher.
Similar to sending email, telephony is a business of volume. The more call you make the less your prices are going to be. I worked in telephony space for a few years, and it's a fascinating industry.