Hello & Welcome to Just Answer,
Sorry to hear of any issue you are having with your phones.
To help you with this issue, may I ask:
1) The Make & Model Number of the phone system you are working with? If this is a cordless system, that model should be printed on a sticker on the bottom or back of the main base unit.
2) What phone service provider (phone company) you have for this phone line?
3) If you have ANY other devices (phones, fax, etc.) attached to this same phone line and if so, are they working properly?
OK - is the service from AT&T a "U-verse" based service - along with internet and perhaps TV service?
OK - so I assume you have U-verse for Internet AND Phone - is that correct?
If so, when you mentioned "resetting your router" - was that the U-verse "box" - with the blinking lights on the front?
OK - if you have the SAME U-verse box that I have, there should be some LIGHTS on the front of the box, and ONE of those light will have a label next to it for "Phone1", and the next light down should be "Phone2".
Are EITHER of those lights ON - or blinking?
Also, have you tried MOVING the phone cord from the MAIN BASE UNIT of your cordless phone - so that it is connected DIRECTLY to the PHONE1 jack - in the back of the U-verse box?
OK - if the PHONE1 light is NOT ON (or blinking), that means that SERVICE is NOT ACTIVE - and would explain why there is no dial tone or ability to take or make calls.
So what I would like you to do is RESET the U-verse box - one more time.
I don't know how you did it before, but the process I recommend is to remove the power connector from the BACK of the U-verse box and LEAVE IT DISCONNECTED for a FULL 2 minutes.
Then RECONNECT the power connector and WATCH (the lights on the front of the box) and WAIT for the lights to "stabilize" into a "normal pattern". Once stable, that PHONE1 light SHOULD be ON - and MAY be blinking.
Once that happens, it would be safe to TEST your phone - by either reconnecting the phone cord to the original phone jack (where it was before all this started), including any filter that was there.
Please give that a try and let me know your results - when you can.
NOTE: This power off reset WILL stop your internet connections, but don't worry, they should come right back after the reboot.
You should even be able to leave this page OPEN and simply REFRESH the screen of the computer to get right back here.
Thanks, ***** *****
While the box was coming back ON, did you see the PHONE1 (or PHONE2) light at least BLINK a little?
OK - if the light is not even "trying" to come on, then that tells us that the PHONE service is not starting.
Now there is a SLIM chance that any phones or phone cords connected to the box could be cause this issue (of no PHONE LIGHT), and you can TRY disconnecting (and leaving disconnected) and phone cords from the PHONE jacks at the back of the box, and try power cycling one more time - to see if the light WILL come on (starting the SERVICE).
But if that does not work (has the same result - no PHONE1 light), then that tells us this is either an equipment issue or a SERVICE issue - coming into the box.
If that is the case, it would be time to contact AT&T - either by a working phone or via internet - and report this issue and have it looked into. I have the contact information below.
AT&T Customer Support : 1(###) ###-####/strong>
Go through menu to reach "Technical Support" or "report a problem"
Look for "Chat Available"
Please let me know if you try the second power cycle reset - with any phone cords disconnected - or if you need to contact support.