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SIP trunking and TTY/TDD messaging

Question is simply with regards to utilization of CU based off of SIP trunks will the SIP trunks carry TTY/TDD messaging reliably?

The reason for this specific question is that CISCO states that TTY/TDD works over VoIP, which I agree, but I can not find where it is practiced with CUCM and SIP specifically. Actually I did find a September 2010 CISCO best practice white paper which declares 

"● Similar to the previous point, keep modem, POS, and telecommunications devices for the hearing impaired (TDD) traffic on TDM trunks for the present. SIP trunk technology is not ready to carry these traffic types reliably and predictably."

located at:

So my question should be clear, not if TTY/TDD works in the IP environment but does it work utilizing SIP Trunks?


David Fudge