ISmsService.cs

public interface ISmsService
{
    public Task Send(string from, string to, string body);
}

public class Twilio : ISmsService
{
    public Twilio()
    {
        TwilioClient.Init("ACCOUNT_SID", "AUTH_TOKEN");
    }
    
    public async Task Send(string from, string to, string body)
    {
        await MessageResource.CreateAsync(
            body: body,
            from: new PhoneNumber(from),
            to: new PhoneNumber(to)
        );
    }
}

public class EventHandlerExample2
{
    private readonly ISmsService _smsService;
    private readonly SmsOptions _options;
    private readonly GetShipmentContact _getShipmentContact;

    public EventHandlerExample2(ISmsService smsService, IOptions<SmsOptions> options, GetShipmentContact getShipmentContact)
    {
        _smsService = smsService;
        _options = options.Value;
        _getShipmentContact = getShipmentContact;
    }
    
    public async Task Handle(Delivered delivered)
    {
        var contact = await _getShipmentContact(delivered.ReferenceNumber);
        
        await _smsService.Send(
            body: $"{delivered.ReferenceNumber} Package Delivered!",
            from: _options.From, 
            to: contact.PhoneNumber);
    }
}