Real-Time Text on 3-way Call

I am using the features.conf file to create a three-way call between a non RTT capable phone (cell phone) and two RTT capable phones. When I dial from the cell phone, I put the call into a queue. A person with an RTT capable in the queue answers and then dials *2 and the extension to dial the other RTT capable phone. The cell phone is put on hold while the other call is established. Once a call between the two RTT phones is established, the queue answerer then dial *3 to connect all of the phones. When I try to test RTT between the two RTT capable phones, nothing happens.

If I start a call from a RTT capable phone, RTT works. This works the same way as stated before, it is just the RTT capable phone calling into the queue, another RTT capable phone answering and joining the calls.

Is there a way to force RTT on these calls?