In a tweet, the company said "Service is starting to come back online. Thank you again for your patience as our technical teams work towards full restoration."
Optimum internet, cable, and phone customers have been experiencing problems since 7:30 Friday night.
Altice spokeswoman Lisa Anselmo said Saturday morning that crews "worked around the clock" and service under the company's Optimum brand is returning to normal.
Earlier, T-Mobile customers lost service temporarily, which is also starting to restore.
People flooded their local stores, trying to figure out what was wrong. Customers were still able to send and receive text messages.
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