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Try another phone. Remember to change cords. Disconnect any answering machines, cordless phones and auxiliary equipment from your phone jacks and see if dial tone is restored.
The cord into the wall does not have 4 wires. Check the clip. Make sure there are 4 wires, not just 2. Make sure it is plugged into the right plug into the back of the phone.
Call your phone company to see if they have finished turning the new number on. If still dead, the problem may be either with your inside wiring or with service from you phone company. You can determine which by checking for dial tone at the NID (MPOE) . Take a working phone to the NID and test the phone service entering your home. (Older homes might not have this) If you have dial tone at the NID, the problem is in your inside wiring. If you do not have dial tone at the NID, contact you phone company repair service.
You might have too many phones in the house. Turn off some bells (ringers).
It is most likely a problem with the telephone itself. Sometimes 2 phones in the house are incompatible. If the phones are different brands, you might want to try using phones from the same manufacturer. You could also try a amplified handset.
Usually this is a problem with the outside wiring and, if so, its the responsibility of the phone company to repair. If you have a cordless phone, answering machine, unplug it first, as they can cause the problem. You can also go to the NID (MPOE) and check there.
If it is a 2-line phone: You should not plug anything into that jack that doesn't accept 2 numbers, like a answering machine, fax, etc. This can cause trouble. Have separate jacks installed for the separate machines you wish to use.
If you have Call-waiting, it probably means that a call is coming in and cutting you off the data transmission. Use *70 (or whatever your local phone co suggests to use) to temporarily disconnect call-waiting as part of your modem dial string.