Sure. If you are saying that $_ has newlines in it, you can just remove them with tr/\n//d. Then process as before.

It may be slightly trickier if you're saying the number is split across lines in an input file that you're reading one line at a time. Basically, you'll want to remember some of the previous line while you read the next line, stick them together, then look for the phone number. Exactly how you work that out depends on what you know about your input.