LTE/5G Field Reference – VoIP & Fax

Use the worst of SINR and RSRQ-type metrics as the Primary Gate. For 5G NR the equivalent metrics are SS‑SINR and SS‑RSRQ. RSRP (or SS‑RSRP) adds coverage margin context; RSSI is least predictive.

Interactive Evaluator

Mode

SINR (dB)

RSRQ (dB)

RSRP (dBm)

RSSI (dBm)

Optional IP Network Checks

RTT (ms)

Jitter (ms)

Upstream Bandwidth (Mbps)

Downstream Bandwidth (Mbps)

RF Performance Thresholds

Metric (LTE)	Good	Caution	No-Go	Why it Matters
SINR (dB)	≥ 13	6–12	≤ 5	Clean vs. noisy link; biggest predictor of jitter/packet loss
RSRQ (dB)	≥ -10	-11 to -14	≤ -15	Cell load/interference → affects stability
RSRP (dBm)	≥ -90	-91 to -100	≤ -101	Reference signal power; coverage margin
RSSI (dBm)	≥ -70	-71 to -85	≤ -86	Wideband power (less predictive than above)

Metric (5G NR – SS*)	Good	Caution	No-Go	Notes
SS‑SINR (dB)	≥ 20	10–19	≤ 9	Higher SINR expected on NR with beamforming
SS‑RSRQ (dB)	≥ -10	-10 to -15	≤ -15	Quality/interference on SSB
SS‑RSRP (dBm)	≥ -80	-81 to -100	≤ -100	Power of SSB reference

*SS = Synchronization Signal block. Thresholds are practical guidance; OEMs may report on different resources (CSI, etc.).

Outcome Matrix

Service	Good	Caution	No-Go
VoIP (Speech)	Clear audio; G.711/Opus OK; low jitter	Usable; occasional chop; prefer Opus; jitter buffer 60–120 ms	Clipping/robotic voice; talk-over; call drops
Fax (T.38)	Reliable	Slow; retries; short faxes may pass; multi-page often fail	Negotiation or mid-page failures common
Fax (G.711)	Only in Good radio & IP: loss <0.5%, jitter <20 ms	Mostly fails; handshake drops; page truncation	Fails almost always; timeouts

IP Network Reference (both LTE & 5G)

Metric	Good	Caution	No-Go	Notes
RTT / Latency	≤ 60 ms (LTE) · ≤ 30 ms (5G‑SA)	60–120 ms (LTE) · 30–60 ms (5G)	> 120 ms	End‑to‑end; depends on core/peering
Jitter	≤ 20 ms	21–40 ms	> 40 ms	Prefer adaptive jitter buffer for VoIP
Upstream BW	≥ 0.3 Mbps (Opus) · ≥ 0.1 Mbps (T.38)	Below good	< 0.1 Mbps	G.711 needs ~0.1 Mbps per direction + overhead

Quick Test Cases

These auto-fill values exercise each path of the evaluator across LTE and 5G NR.

Tip When RF looks good but calls still suffer, check the IP network: RTT, jitter, and upstream bandwidth. IP problems can degrade quality even when the RF Primary Gate is Good.