from otp_twilio.models import TwilioSMSDevice
from accounts.models import User
phone = "+38050ххххххх"

device, created = TwilioSMSDevice.objects.update_or_create(
    user=u1, defaults={
        'name': 'SMS {}'.format(u1.pk),
        'number': str(phone)
    }
)
token = device.generate_challenge()