ASR = Automatic Speech Recognition

ASR is a measure of network quality defined in ITU SG2 Recommendation E.411: ‘International network management - Operational guidance’.

Some products & makers

• Sphinx (open source)
• Loquendo
• Nuance
• Telisma
• IBM
• Siemens
• Sympalog

See also

• TTS: Text-to-speech

ASR = Answer Seizure Ratio

Its calculated by taking the number of sucessfully answered calls and dividing by the total number of calls attempted (seizures). Since busy signals and other rejections by the called number count as call failures, the calculated ASR value can vary depending on user behaviour.

NER = Network Efficiency Ratio

NER has been proposed as an addition to ITU E.411. It is designed to eliminate user behaviour as factor and better represent pure network performance.

Its calculated as: (Answers + User Busy + Ring No Answer + Terminal Rejects) / Total call attempts (seizures)


Since the ITU documents are not freely available on the Web, this document may be useful:
P813-PF Technical Development and Support for European ATM Service Introduction, Deliverable 5, Recommendations on Traffic-related Implementation Issues, Volume 2 of 4: Annex A - Methods for Call-level Congestion