If you were activated/approved without Spending Limit program, you can have up to 3 lines for the first 90 days of activity and then up to a max of 5 after that.
If you're still currently on SLP, then you'll have to wait until it's eligible to be removed, then you'll have up to 5 lines.
So, in a roundabout way of answering your question: yes. Log into Self Serve and in the bottom left corner it will say if you're on SLP or not. If you are, then call them and ask when it can come off. If you aren't, then go get more phones for your parents/brother or sister/dog/second uncle's twin brother's twice removed stepdad's son.