With NoKSU telephones, there are a few ground rules to keep in mind.
1) Each station must have the same telephone line assigned to Line #1.
2) Each unit must be assigned a specific extension number during installation.
3) If there is DSL service on any of the telephone lines, the telephones must be wired behind the filter.
4) With NoKSU units, you are limited to what other telephones can be used in the system. The AT&T 944 had only 2 siblings....the 955 & 964.
I would check to make sure that each unit has a unique extension number.
Lastly...the 944, 955 & 964 (Manufactured for AT&T by VTech) have been off the market for several years now. The current at&t branded NoKSUs will not integrate with the 944's.
(Oops...TTT posted before I did.

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