Last week in our forum, discussions were diverse and engaging. Members delved into the technical nuances of POTS voltage and shared insights on managing network issues post-outage. Practical challenges like temporary firewall rules and pre-launch audit trails sparked thoughtful exchanges. The human side of telecom was also present, with stories of high-altitude repairs and the quirks of asset management.
This Week’s Hot Topics
Why POTS runs on 48 volts
Ever wondered why POTS uses 48 volts? This thread unpacks the historical and technical reasons behind this choice. Read more here
What ‘deprioritized’ really means on unlimited plans
Clarifying the fine print on data plans, this discussion sheds light on how deprioritization affects your service. Read more here
The immortal “temporary” firewall rule
Explore why some temporary firewall rules never seem to go away and the implications for network security. Read more here
When ‘seamless’ meets the change window
This thread discusses the real challenges of implementing “seamless” changes during maintenance windows. Read more here
Windy swap at 220 feet today
A firsthand account of replacing equipment at dizzying heights, highlighting the risks and rewards. Read more here
What belongs in a pre-launch audit trail
Gain insights into what should be documented before launching a new service to ensure accountability and compliance. Read more here
Cutting repeat calls after outages
Strategies for reducing repeat customer inquiries post-outage are shared in this practical discussion. Read more here
When asset tag 04137 learned to teleport
A lighthearted tale of a wayward asset tag that seemed to have a mind of its own. Read more here
POTS ring is ~90 VAC at 20 Hz
Discover the technical specs behind the POTS ring signal and why they matter. Read more here
Looking forward to another week of engaging discussions. Keep sharing your experiences and insights.
On the POTS side, when I’m chasing weird dial tone after a post-outage, I clip a 1 kΩ resistor across tip/ring with a DMM — on-hook should sit around the ‘48 volts’ and drop to about 6–10 V; if it doesn’t, you’ve got an open or a bad battery feed. It’s saved me from climbing to the aerial splice more than once, though beware some ATAs sit a bit higher and won’t drop cleanly under that load, so confirm the source first.
Building on @mike_ross87, I skip to loop current: off-hook “20–30 mA” with about 48 V idle is my quick tell; if it’s low, I start hunting for a wet splice or half-tap — 48 V is the Goldilocks that makes it obvious. Caveat: some remotes/ATAs sit closer to 42–50 V, so verify the source before rolling a truck.
Quick tip: after an outage, if idle sits near −48 V and dial tone’s fine but billing/CPE triggers act weird, I watch for “battery reversal” on answer — if it never flips, the line card’s wedged, not a copper fault… Caveat: some SIP ATAs don’t reverse at all, so don’t chase ghosts; @sandra_kay23, seen that bite people?
I’ve saved time by watching ring-trip instead of staring at idle voltage: you should see the about 90 VAC superimposed and a clean drop when the set answers; if it never trips, the ringer/REN load is suspect… Caveat: on DLC/ATA ports the ‘48 V’ and ring amplitude are profile-driven, so check the config before hunting copper ghosts — @mike_ross87’s loop-current point still applies.