To find the total storage after buying the additional bytes, we start with the storage amount in scientific notation and then add the additional bytes.
- The current storage is \( 1.28 \times 10^{11} \) bytes.
- The additional storage is \( 384,000,000,000 \) bytes.
Next, we convert the additional storage into scientific notation:
\[ 384,000,000,000 = 3.84 \times 10^{11} \text{ bytes} \]
Now we can add the two quantities:
\[ 1.28 \times 10^{11} + 3.84 \times 10^{11} \]
Combining these:
\[ (1.28 + 3.84) \times 10^{11} = 5.12 \times 10^{11} \text{ bytes} \]
So, if you buy the additional bytes, your phone would have a total storage of:
\[ \boxed{5.12 \times 10^{11}} \]