To find out the total storage of the phone after purchasing the additional bytes, start with the original storage and add the additional storage together.
- Original storage: \( 1.28 \times 10^{11} \) bytes
- Additional storage: \( 384,000,000,000 = 3.84 \times 10^{11} \) bytes
Now, add the two amounts:
\[ 1.28 \times 10^{11} + 3.84 \times 10^{11} \]
This can be rewritten as:
\[ (1.28 + 3.84) \times 10^{11} = 5.12 \times 10^{11} \]
Therefore, the total storage of the phone after buying the additional bytes is:
\[ \boxed{5.12 \times 10^{11}} \]