Every character on Jiǎoluò Shūwū read as bi in any tone — 2 readings total across the four tones. Pick the tone you mean.
If you have the sound bi but not the character, here are the 2 characters read this way: 笔 (bǐ, pen, brush, a stroke, writing), 必 (bì, certainly; must; necessarily). They split across 2 tones, so the tone is what separates them.