Most likely you can still trade as long as you are not opening and closing position during the same day. I.e. not day-trading.
I have just experienced this with IB. When you open a new position, if you account value is below $25K, your order will be rejected. The checking is in real time, as soon as your account value rises above 25K, you can do unlimited day trading again. If your account is below $25K and you want to open new positions, you have to ask your broker to reset your account, it'll take 5 business days. If you hate waiting, adding fund is a much better choice.
I have 2 accounts with two brokers (scottrade and etrade) with a combined total of 13,000 cash usd. this week, i decided to open "boxed positions" where you enter two opposing postions (going long and shorting) of the same security to protect against movement in price and exit both positions the next day rather than use up my 3 pdts per 5 day rolling period. i thought this would be clever and I could kind of get around the pdt rule. ive done this for a week in my scottrade account and ive opened two boxed positions in my etrade account. ive entered 16 trades and exited 12 of them since 2/22 ive already asked etrade to reset my account once due to a misunderstanding of whether entries or exits were counted... WILL I GET A MINIMUM EQUITY CALL? OR WILL MY ACCOUNTS BE RESTRICTED IN ANYWAY?