I believe Wik is referring to a wired house phone that is connected to a wired phone system. We got rid of our wired house phone years ago and even though we all have cell phones in our house we still have a VOIP (Voice Over Internet Protocol)Phone. The voip only costs $4.00 a month. In Canada cell phone service is expensive. It was cheaper to have a home phone VOIP service to call anywhere in Canada or the USA than a cell plan that does the same.
If I remember correctly our old original phone system had 4 wires of which only 2 were used. We live in a rural area and the Phone Company technician had to come out and rewire our phones to use the other pair of wires when one pair of wires failed. After a few more years the technician had to replace the buried outdoor cable which also failed. I was surprised that the outdoor cable is only buried a few cm's below the lawn. When we finally got high speed internet it was the same thing the fiber cable cable is only just below the lawn. The 4 wires may be required if you have a party line. I had on of those in my previous home and I answered the phone only after hearing 2 long and one short ring.
If I remember correctly our old original phone system had 4 wires of which only 2 were used. We live in a rural area and the Phone Company technician had to come out and rewire our phones to use the other pair of wires when one pair of wires failed. After a few more years the technician had to replace the buried outdoor cable which also failed. I was surprised that the outdoor cable is only buried a few cm's below the lawn. When we finally got high speed internet it was the same thing the fiber cable cable is only just below the lawn. The 4 wires may be required if you have a party line. I had on of those in my previous home and I answered the phone only after hearing 2 long and one short ring.
The 4-wire drop is so you can add a Princess phone for your teenage daughter. Good profit in that racket!
And as you say, a spare. Or added confusion when my telco insisted on swapping the pairs at the street, then at the pole, then in the cellar. They were making the installed plant match the documentation. (Last gasp before they sold-out.)
And yes, I've nearly hit my line with the lawnmower. Snag a tree-rootlet, which grew under the line, it comes up.
My neighbor's TV/Net cable went out mid winter, they threw an orange line on top of the snow/ice, said they would be back in spring. Still there 7 years later. Maybe that is the best way!
Buried power line too, for extra fun.
I have optical fiber coming (I hope and pray). May be interesting to see how they bring that in. Since the house grew an extension, "follow the phone wire" is no longer the best strategy.
And as you say, a spare. Or added confusion when my telco insisted on swapping the pairs at the street, then at the pole, then in the cellar. They were making the installed plant match the documentation. (Last gasp before they sold-out.)
And yes, I've nearly hit my line with the lawnmower. Snag a tree-rootlet, which grew under the line, it comes up.
My neighbor's TV/Net cable went out mid winter, they threw an orange line on top of the snow/ice, said they would be back in spring. Still there 7 years later. Maybe that is the best way!
Buried power line too, for extra fun.
I have optical fiber coming (I hope and pray). May be interesting to see how they bring that in. Since the house grew an extension, "follow the phone wire" is no longer the best strategy.
Which country uses the word handphone?
Noun. (Indonesia, Malaysia, Myanmar, Singapore, South Korea) A mobile phone.
handphone - Wiktionary
Probably this is battery from mobile phone ,looks like older model ,newer ones are not user so easy changeable. Pins marked "+" and " -" are power output from battery , other two is data, maybe i2c or other protocol. If you wanna power up phone from psu , without battery ,some may work, some not , depends on controller / software . You may measure voltages on all pins of that battery , and then resistances, if on some pins voltage would look identical. As i know , battery itself don't need communication to operate , but device may search for battery and not turn on if it's not detected.
It's too funny that even after he added a picture, nobody answered his question. AFAIK battery packs that have 4 terminals have 1 that gives you a charge indicator and 1 that gives you battery temperature as well as the 2 for pos and neg of course.
EDIT: ximikas beat me to it
EDIT: ximikas beat me to it