Panasonic cordless phones no dial tone but landline connected directly to modem is working. When I tried plugging the cordless into the modem directly it still doesn't work It states "check tel line"

Firstly, disconnect all devices / base unit from your landline. Then, using a mobile phone, dial your landline number. Does the ringing tone in the earpiece continue or does it stop after one ring? If it stops then you have a line problem which you need to report to your service provider.

although the computer and the telephone use the same line, they do not use the same system
frequency for a telephone is vastly different to adsl and it is in the exchange that the difference occurs
get ( borrow) an old phone and plug it into the socket and if you have a dial tone , it is the cordless system that is faulty
if the batteries are recommended at 1.2 vo then that is what you should be using as that is what the phone frequency will be set to use

Troubleshooting Home Phone for No Dial Tone ' iiHelp

https://iihelp.iinet.net.au/Troubleshooting_Home_Phone_for_No_Dial_T...

This article will explain what to do if you can't make or receive calls using your HomePhone (landline). ... If it rings normally, skip to step 3. If you hear an engaged tone ora recorded voice saying the number is not available, ... If you have a dial tone and can make a call when your phone is plugged into one socket but not ...
No Dial Tone - Phone Forum - Phone Forum - Cox Support Forumsforums.cox.com/forum_home/phone_forum/f/6/t/3496.aspxJan 1, 2014 - 16 posts - ‎13 authorsThis will help determine which phone or jack may be contributing to the problem. If these steps do not restore your phone service it may be necessary to ... directly to the #1 telephone port on the modem and see if you get dial tone there. ... Then try calling yourself(from a cell phone), and as it rings, plug the ...Big Mystery...Phone won't ring ' Techlore

You could plug your non-cordless phone into suspicious phone jack to see if you have dial tone-if you dont have dial tone, the line maynot be connected and you should open the jack to see if there is more than 1 cable attached. If there is more than 1 cable attached and you dont have dial tone at other end of cable the cable might be cut or shorted somewhere inbetween. You can test continuity by tying 2 wires together and test with a multimeter on resistance to see if it is open circuit or maybe even short circuit. To test for short circuit, untie the cables and you should not get a reading. If you do have dial tone when you plug in non-cordless phone the distance might be to far for receiver to pick it up(ie..greater than 10 metres). I hope this has been helpful.

Do you even hear white noise? If not, it sounds like your phone's speakers may be broken, or it has water damage. If your landline is connected to more phones, ask yourself these questions:

Do all of the phones have this problem? If so, it's a problem with your connection, not the speaker.

Is there a volume button anywhere on the phone or the base? Try turning it up.

Do my phones make a "beep" noise when i push the buttons? If not, did they used to? If they don't, then it's likely that the speaker is no longer working properly.

You may need to contact panasonic and see if they will replace it for you.

Hope this helped! Please rate my solution!
- Frankie

Try phoneing or e mailing the number or e mail address on the box or manual of the phones where you bought them from or get in touch with the company that made them and ask for either a refund or technical help. If your landline is working the storm has disconnected something with the base of your phones

There are two possible answers to this problem. The first thing is to check on the cordless phones, is a 2 way switch, one setting is for DP=Dial pulse (setting for old rotary phones) 2nd setting is TT= Touch Tone. I would guess that the setting should be set to TT on both cordless phones for touchtone.
Second thing to do is to plug in the base unit of your cordless phone to a jack that currently has a landline phone plugged into it that works and test again. If cordless phone works OK then go back to the original jack that didn't work and reverse the wires in the jack: that is what is known as a "polarity" issue.

Typically, a fax machine is connected directly to a telephone wall jack with a known working connection. Try plugging the fax machine directly into a wall jack first and pick up the handset on the fax machine if it has one. You should get a dial tone. Then try to fax something to someone you know.

The machine can also usually be routed through the modem in a computer by connecting the "line" cord on the modem to the wall jack and plugging the fax machine into the the "phone" jack on the modem. You may need to install the software that came with the fax machine to get this to work.

If you have no dial tone, check the wall jack with a known to be working single line phone. If there is a dial tone, it's something to do with fax machine, the computer modem or the connections.

Some fax machines can take advantage of internet faxing through a cable modem or DSL connection. Check your manual for the options available.

check dialing mode matches what exchange is set to DTMF suspect phone is set to dec = decadic or pulse

Check if the cordless works on a normal telephone line,Plug in another instrument to see if you get dial tone,light.
That's it you should know what is causing the problem.
Samir