I guess he is not eligible for that site as he is a new user, there's a waiting list for that site, so it's not possible for him soon.
Also, I think the volume for such exchange is low and OP is looking to buy a good amount of bitcoin.

For now, only coins.ph is the most convenient, the risk is low of getting scam or actually no risk, but you have to pay the difference.

If you will buy bitcoin at today's price.

http://preev.com/btc/php - 475,700
Coin.ph  -  485,138

So the difference is only 2%, that's really huge if you are buying at least 1 BTC as you need to pay an extra of php 10,000.

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Other suggestion, check this thread also, https://bitcointalk.org/index.php?topic=5108813.0, that explains how to cash out, but I think you can also deposit in bittrex with fiat, you just need to open a usd bank account.