Send Twilio a redirect Uri to another action in the same controller - asp.net-core-mvc

Question

I'm trying to send Twilio a redirect URI to another action in the same controller. I can't give a fully formed Uri because I'm in development and I'm using localhost. I thought I would use a relative Uri. The way it is written, I keep getting fed back in to "Welcome" when I'm trying to redirect to "RouteCall".
As a side note, routing in MVC seems very redundant. I couldn't get routing to work without explicitly using the Route tags that you see.
using System;
using Microsoft.AspNetCore.Mvc;
using Twilio.AspNet.Core;
using Twilio.TwiML;
namespace centurionvoice.Controllers
{
[Route("[controller]")]
[ApiController]
public class VoiceController : TwilioController
{
[Route("welcome")]
public IActionResult Welcome()
{
Uri newUri = new Uri("/RouteCall", UriKind.Relative);
var response = new VoiceResponse();
response.Say("Thank you for calling. To do some thing, press 1. To do another thing, press 0.");
response.Gather(numDigits: 1);
response.Redirect(newUri);
return TwiML(response);
}
[Route("routecall")]
[AcceptVerbs("GET", "POST")]
public IActionResult RouteCall(string digits)
{
var response = new VoiceResponse();
if (digits.Equals("1"))
{
//Dial the someone else
response.Say("You are being trasferred.");
return TwiML(response);
}
else
{
//Record a message
response.Say("Please record your message.");
response.Gather();
return TwiML(response);
}
}
}
}

Answer 1

The first thing I did was modify Startup.cs to configure basic/intuitive routing.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
app.UseHttpsRedirection();
app.UseRouting();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
{
endpoints.MapControllerRoute(
name: "default",
pattern: "api/{controller=Voice}/{action=Index}/{id?}");
});
}
Then back in VoiceController, new Uri() didn't throw errors anymore:
[HttpPost]
public IActionResult Index()
{
var response = new VoiceResponse();
var gather = new Gather(numDigits: 1, action: new Uri("/api/voice/gather", UriKind.Relative));
gather.Say("To do one thing, press 1. To do another thing, press 0.", voice: "Polly.Nicole");
response.Append(gather);
// If the user doesn't enter input, loop
response.Redirect(new Uri("/api/voice", UriKind.Relative));
return TwiML(response);
}