I will try.
My interpretation (I have had no confirmation that this is true) is that the problems are related to the differing standards specification. The following is a gross over-simplification, but;
The GSM standard defines the operation of the entire network and is a true global standard (as the name implies). In comparison, IS-95 (a.k.a. cdmaOne) is a specification that defines
only the air interface, i.e. the manner in which the phone connects to the cell tower. This means that the services that are offered, and how they are provided is entirely up to the network provider.
As the way to access a GSM-based service (and which services are provided) is strictly defined, it means that 3rd-party systems can access services over GSM according to the published GSM standards. The way to access a particular service over CDMA can be (and is) completely different for every provider (as handsets are tied to a particular provider this is not a problem for the provider). Unless operators specifically allow 3rd-party access to their network services (by providing the required information) such access is not possible.
So, I don't think that your TT
cannot issue the correct commands, but that it doesn't know those commands. It could issue them if it knew them. Unfortunately, that is a secret known only to your network operator.
Combine the above with the fact that GSM is used by 85% of the mobile world and CDMA is only used by 10% and you can see why 3rd parties (in this case TomTom) are either unable or unwilling to provide support for CDMA phones.
