If you already have a block diagram of the typical cell phone, then it might be useful to look at a photo of the circuit board to understand what ICs do which jobs. One way to find such photos is to search on keywords "cell phone tear down". Here is one typical link:
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One way to find a block diagram of a cell phone is to find application notes from the suppliers of the major ICs inside them.
Here is an example:
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Unfortunately, this are over-simplified. For example, in the above example, the RF transceiver is a single box when in fact it is a complex subsystem with many functions.
Here is another link of cellphone architecture from a software point of view:
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Here are some more diagrams:
https://www.ti.com/sc/docs/psheets/diagrams/gsmhand.htm
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search on these keywords:
GSM Handset block diagram
GSM mobile phone theory of operation
CDMA handset block diagram
UMTS mobile phone block diagram
etc.