| ¤ | The TN QUALITY & SIGNALLING ANALYSER EQS 133A for measuring signalling and traffic parameters between analog, PCM and ISDN telephone exchanges. |
| ¤ | The TN QUALITY & SIGNALLING ANALYSER EQS 133D test set can be used for testing PCM (two HDLC framed full duplex CCS links at the same time) and ISDN exchanges. |