| Business | Phone |
| A Phone-Tech & Cable Comm 68 Lafayette St, Waltham 2453 | (781) 893-6200 |
| Abacus Group 296 Newton St, Waltham 2453 | (781) 891-3300 |
| Associated Voice & Data Svc 150 Lexington St, Waltham 2452 | (781) 894-8900 |
| Ctc Communications Corp 220 Bear Hill Rd, Waltham 2451 | (781) 466-8080 |
| Hcs Telesystems Waltham 2453 | (781) 647-5549 |