Extensions don't ring

Check the lines using a hardwired phone plugged into the master sockets, remove any extensions if possible and listen again. Make sure if you have any ADSL filters installed they are removed and the broadband router if you use one.

if the problem persists you'll need to call the Service provider.

Sound like a short issue between the two lines.

Hello. Often the aftermath of a power outage is a power surge. If your phone system is not surge protected, this is the likely culprit. The damage done by a surge or several surges can only be assessed with a thorough diagnostic exploration. This has to be done by a technician with the proper diagnostic equipment and know how. j.

Sounds like the system defaulted programming.
Depending on the type of prostar 616 the only ringing station would be 1(or 21) with the porstar or 4(or 24) with the prostar plus.
To change the ringing on a prostar 816 you first need to be at a display set (doesn't matter what the extension number is).
with the handset down, enter #20 the screen should say MMC DISABLED
enter in 1 2 3 4 1 # (that enables programming)
enter in #62 the screen should say day ring assn
press the line you wish to program
press the buttons for the extensions that you wish to ring (the ones in the right next to the handset)
press # when finished with the line
repeat steps 2 through 5 for the remainder of the lines you wish to change
press # when finished.
To program system speed dial numbersyou need the customer programming enabled (see the first part of programing ringing)
press the ALM/SD button
dial the 2 digit speed dialcode 10-98
dial the telephone number to be stored in that speed dial bank
press ALM/SD to store the number

Your voicemail thinks that it is ringing six times. The time that it takes to transfer to the extensions counts. Whiloe it seems that there is a lapse the system actually is using enough time to ring six times total. If you need longer ring time at the extension, take in account the transfer time and set it to pick up after 8 or 9 rings. It will actually only ring six. You just have to trick the system a little.

Your system lost its programming. It will need to be reprogrammed completely. The lines are ringing on the extensions where I voicemail is, unplug voicemail and at least lines will ring in correctly.

To change the ringing on a prostar 816 you first need to be at a display set (doesn't matter what the extension number is).
with the handset down enter #20 the screen should say MMC DISABLED
1) enter in 1 2 3 4 1 # (that enables programming)
2) enter in #62 the screen should say day ring assn
3) press the line you wish to program
4) press the buttons for the extensions that you wish to ring (the ones in the right next to the handset)
5) press # when finished with the line
6) repeat steps 2 through 5 for the remainder of the lines you wish to change
press #when finished. hope that helps

To change the ringing on a prostar 816 you first need to be at a display set (doesn't matter what the extension number is).
with the handset down enter #20 the screen should say MMC DISABLED
1) enter in 1 2 3 4 1 # (that enables programming)
2) enter in #62 the screen should say day ring assn
3) press the line you wish to program
4) press the buttons for the extensions that you wish to ring (the ones in the right next to the handset)
5) press # when finished with the line
6) repeat steps 2 through 5 for the remainder of the lines you wish to change
The code for hold recall is #52
enter in your hold recall time in sec. and in a 3 digit format. i.e. 30 seconds = 030 a minute and a half is 090 and so on.
press # when finished

it sounds like the memory battery on the main board is no longer working which means that it'll happen again.

The system lost programming. Call a vendor in...

Must reset all extensions with individual extension numbers after a power outage. Just the same as starting the phone out of the box. Thanx.

There is a small battery inside your main control unit that keeps programming in memory during a power outage. The life of the battery is about 5 years give or take. When the system goes down for an extended period (or possibly several quick on/off cycles) your programming will be wiped out. By default, only a few telephones will ring. The battery is most likely a small blue 3-cell battery soldered right on the main board. It's not easily replaced. You can get a technician to replace it or hook up a standard battery backup unit (UPS) made for a computer. Your phone system uses less power than a computer so it can use any UPS and will last longer than advertised. Hard to say exactly how long. Just don't re-program the system until you take care of the problem or it will just default on you again.