1. Make sure that there is Bulgarian keyboard in Settings > General > Keyboard > Keyboards.
2. Additionally, make sure that Automatic or Bulgarian - Phonetic is selected for the Bulgarian keyboard in Settings > General > Keyboard > Hardware Keyboard.
3. The Bulgarian language code is BG, represented by the numeric 8, 8.
4. The language at L3 can be any Roman alphabet language. The initial factory setting is English.
5. The language at L4 can be any language. The initial factory setting is none.
6. The Bulgarian language can be set at L4.
7. To set the Bulgarian language at L4, press L3 + L1, L4, 6, 8, 8.
8. To unset the language at L4, press L3 + L1, L4, R1.
9. Roman alphabet letters and common keyboard symbols are as in Rivo alphabet layout and Rivo symbols layout.
10. Letters in Bulgarian are assigned to each number button as follows:
| 2 | а, б, в, г |
| 3 | д, е, ж, з |
| 4 | и, й, к, л |
| 5 | м, н, о, п |
| 6 | р, с, т, у |
| 7 | ф, х, ц, ч |
| 8 | ш, щ, ъ |
| 9 | ь, ю, я |
11. Symbols are assigned to each number button as in Rivo Symbols Layout, with the following exception:
| # | number sign, euro sign, pound sign |