GSM is a type of TDMA, you are correct, not sure how that matters.
Read your own statement:
What both of these do is have multiple services in the same radio bandwidth. The difference is how they do it, but it is still the same radio frequency. Yes, sms does not use the same amount of frames as voice but that is not what you said but probably what you meant.
CDMA was developed in Europe, TDMA in North America, yet most europe uses TDMA.... I let you draw your conclusion.
Again, as I explained before, voice and sms works in the same CDMA or TDMA radio signal. The difference is sms takes lot less time to send a 10 lines text with 500 words total than what it takes for a person to:
notice their phone has signal.
dial the number.
the other person pick up the phone.
you say your 500 words.
Finish the call...
All of the above without interruption due to spotty signal....