Hellotel ts-250 handsfree dial telephone price in bangladesh Hellotel TS-250 is a hands-free dial telephone suitable for apartment management. The telephone buttons on it are very smooth, and comfortable so it doesn’t create any obstruction while dialing. These telephones have Dual-Tone Multi-Frequency (DTMF) technology in which tones are transmitted over the voice channel when numbers are pressed by the telephone and are used to control automated equipment and signal user intent.