| Accessories | |
| IPX-21BR | 4-Port ISDN Module for IPX-2100 / IPX-2500 (Basic Rate Interface) |
| IPX-21FO | 4-Port FXO Module for IPX-2100 / IPX-2500 |
| IPX-21GS | 4-Port GSM Module for IPX-2100 / IPX-2500 |
| IPX-21PR | 1-Port ISDN Module for IPX-2100 / IPX-2500 (Primary Rate Interface) |
| IPX-21SL | 4-Port Life-Line module for IPX-2100 / IPX-2500 (2FXO + 2FXS) |