Metrics Glossary

Quick reference table of all 69 CallMeter VoIP metrics organized by category, with keys, units, and links to detailed documentation.

This glossary lists every metric CallMeter collects during test and probe execution. Each metric links to its detailed documentation page with thresholds, measurement methodology, and troubleshooting guidance.

For an introduction to how metrics work, see the Metrics Reference overview.

Quality

Core VoIP quality scores that summarize call experience into actionable numbers.

Metric	Key	Unit	Description
MOS Score	`mos`	1-5	Mean Opinion Score — overall voice quality rating (E-model, G.107)
R-Factor	`r_factor`	0-100	Transmission quality rating (G.107)
Jitter	`jitter_ms`	ms	Inter-arrival time variation
Round Trip Time	`rtt_ms`	ms	Network round-trip latency
Packets Lost	`packets_lost`	packets	Cumulative lost packet count
Packet Loss Rate	`fraction_lost`	%	Percentage of packets lost per interval
Clock Drift	`clock_drift_estimate`	ppm	Hardware clock frequency accuracy
Clock Skew	`clock_skew_estimate`	ppm	Sender-receiver clock offset
Timestamp Jumps	`timestamp_jumps`	count	RTP timestamp discontinuities

Network

Transport-layer packet and bandwidth measurements.

Metric	Key	Unit	Description
Packets Sent	`packets_sent`	packets	Total RTP packets transmitted
Packets Received	`packets_received`	packets	Total RTP packets received
Bytes Sent	`bytes_sent`	bytes	Total payload bytes transmitted
Bytes Received	`bytes_received`	bytes	Total payload bytes received
Send Rate	`packets_sent_rate_ps`	pps	Outbound packet rate
Receive Rate	`packets_recv_rate_ps`	pps	Inbound packet rate
Send Bitrate	`bytes_sent_rate_bps`	bps	Outbound bandwidth
Receive Bitrate	`bytes_recv_rate_bps`	bps	Inbound bandwidth
Duplicate Packets	`duplicate_packets`	packets	Packets received more than once
Out-of-Order	`out_of_order_packets`	packets	Packets arriving out of sequence
Sequence Resets	`sequence_number_resets`	count	Sequence number counter restarts
Sequence Gaps	`sequence_number_gaps`	packets	Burst loss event sizes
Sequence Jumps	`sequence_number_jumps`	count	Large sequence discontinuities
Max Spacing	`max_packet_spacing`	ms	Largest inter-packet gap
Min Spacing	`min_packet_spacing`	ms	Smallest inter-packet gap
Avg Spacing	`avg_packet_spacing`	ms	Average inter-packet gap

Feedback

RTCP feedback messages exchanged between endpoints for error recovery and quality adaptation.

Metric	Key	Unit	Description
NACK	`nack_count`	count	Negative acknowledgement requests (packet retransmission)
PLI	`pli_count`	count	Picture Loss Indication requests (video keyframe)
FIR	`fir_count`	count	Full Intra Request (force keyframe)
SLI	`sli_count`	count	Slice Loss Indication
SIP INFO PFU	`sip_info_pfu`	count	SIP INFO Picture Fast Update requests

Jitter Buffer

Receiver-side adaptive buffer metrics showing how well the endpoint handles network jitter.

Metric	Key	Unit	Description
Current Delay	`jitter_buffer_delay`	ms	Current buffer depth
Target Delay	`jitter_buffer_target`	ms	Adaptive target buffer level
Late Packets	`jitter_buffer_late`	packets	Packets arriving after playout deadline
Average Jitter	`jitter_buffer_avg_jitter`	ms	Buffer-observed jitter estimate
Packet Losses	`jitter_buffer_losses`	packets	Packets declared lost by buffer
Duplicates	`jitter_buffer_duplicates`	packets	Duplicate packets detected by buffer
Packets Pushed	`jitter_buffer_pushed`	packets	Packets pushed out for playout
RTX Requests	`jitter_buffer_rtx_requests`	count	Retransmission requests sent
RTX Success	`jitter_buffer_rtx_success`	count	Successful retransmissions received

Audio

Audio-specific quality measurements and codec diagnostics.

Metric	Key	Unit	Description
PLC Events	`plc_events`	count	Packet Loss Concealment activations
PLC Duration	`plc_duration`	ms	Total concealment time
Signal Level	`audio_signal_level_rms_dbov`	dBov	Audio signal power
Noise Level	`audio_noise_level_rms_dbov`	dBov	Background noise power
Speech Activity	`vad_speech_ratio`	%	Voice activity detection ratio
Comfort Noise	`comfort_noise_inserts`	count	Comfort noise generation events
Opus Bandwidth	`opus_bandwidth_khz`	kHz	Opus encoder operating bandwidth
Opus Decoder Gain	`opus_decoder_gain_db`	dB	Opus decoder output gain
Opus Packet Loss	`opus_packet_loss_pct`	%	Opus internal packet loss estimate
Opus Packet Duration	`opus_last_packet_duration_ms`	ms	Last Opus frame duration
Audio Level	`audio_level_rms_dbov`	dBov	Combined audio level measurement

Video

Video encoding, playback, and quality measurements.

Metric	Key	Unit	Description
Keyframe Requests Sent	`keyframe_requests_sent`	count	PLI/FIR requests transmitted
Keyframe Requests Received	`keyframe_requests_received`	count	PLI/FIR requests received
Keyframes Sent	`keyframes_sent`	count	I-frames transmitted
Keyframes Received	`keyframes_received`	count	I-frames received
Video Bitrate	`video_bitrate_bps`	bps	Video stream bandwidth
Video FPS	`video_fps`	fps	Frames per second
Resolution	`resolution`	pixels	Current video resolution (WxH)
Keyframe Interval	`keyframe_interval_ms`	ms	Time between keyframes
Freeze Count	`video_freeze_count`	count	Video freeze events
Freeze Duration	`video_freeze_duration_ms`	ms	Total freeze time

Call Timing

One-shot SIP signaling measurements captured once per call.

Metric	Key	Unit	Description
Time to Trying	`time_to_trying_ms`	ms	INVITE to 100 Trying
Time to Ringing	`time_to_ringing_ms`	ms	INVITE to 180 Ringing
Post-Dial Delay	`pdd_ms`	ms	INVITE to first ringback indication
Call Setup Time	`call_setup_ms`	ms	INVITE to 200 OK
Time to First Media	`time_to_first_media_ms`	ms	INVITE to first RTP packet
Call Duration	`call_duration_ms`	ms	Total call length
Final Status Code	`final_status_code`	code	SIP response code ending the call
Call Result	`call_result`	enum	Overall call outcome classification

Metrics Reference — Detailed introduction and usage guide
Analyzing Results — How to interpret test run metrics
Poor Quality Metrics — Troubleshoot quality degradation

Metrics Glossary

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