Voipmich not passing DTMF to some destinations
 

This is a problem with most toll-free termination providers. I'll use tf.voipmich.com in this example.

This problem happens often when calling a large toll-free user (example: IBM on 1-800-426-7378) that has an IVR system that doesn't provide 'answer supervision' until the call is connected to a human. Often, their contracts don't require them to pay minutes for the IVR portion of the call; they signal 'answer' to their carrier when billing is to start. In SIP terms, this means that you get a 183 Progress response when the IVR comes on, but there is no 200 OK until a human picks up.

Apparently tf.voipmich.com doesn't send any media packets (audio and tones) to the destination number until after the destination sends them a 200 OK. This means that you hear the IVR but can't control it with DTMF or with speech.

I think someone at tf.voipmich.com can fix this, but I don't know who to call. Does anyone have contact details for someone at Voipmich.com?