I have a CDMA cellular provider and I have noticed that when sending
text messages to certain people sometimes my messages are never
delivered and vice versa, sometimes I never get a message someone
sends to me. This problem only seems to happen when sending messages
to and from someone who is on a GSM network, specifically T-Mobile.

What I am wondering is, do GSM and CDMA systems have different
protocols for handling the way a text message is delivered. That is to
say that, in this case, CDMA systems have a protocol that ensures the
message is delivered to the handset whereas the GSM systems don't.