Teletherapy should be just as effective. I am a teletherapist right now and if you find an experienced teletherapist you should be fine. You may want to talk to the therapist first---ask about experience with stuttering therapy and how they would structure therapy-such as what approaches they would use. If you go to the ASHA website you should be able to find therapists that specialize in fluency disorders and I would think therapists who will provide that service online.