Using a real phone number for testing

I need to write a test for a service that does two factor authentication using phone numbers.

I need to account for two scenarios. Text and Phone call.

In the phonecall case, a call has to be sent to a real number, the call has to be picked up and a pre-determined code has to be entered by the user who picks up the phone call.

In the SMS case a code is sent to the user and it has to be typed into the web page.

I need a service (paid or free) which provides an API to pickup phone calls and/or read an SMS, to write these tests.

The main important thing here is that the service needs to be reliable otherwise test failures will happen, which is annoying.

Does anyone know of any such services, is there a way to write a wrapper around google voice or similar service to do this?