Pag sa coins.ph, wala talaga tayong way para makapag sign message kasi hindi natin alam ang private keys ng bitcoin wallet natin.
Just a reminder: it also means that you don't really own the bitcoins. If coins.ph would get hacked, go bankrupt or simply runs with the money - you would lose it all. That's why it's better to use a wallet where
only you have access to the private keys.
Coins.ph is additonally bad because they only give 1 address per account (or 2 if including peso wallet.) Much more privacy if they wouldn't re-use addresses.
That being said, I still use coins.ph as easy "prepaid load top-up wallet"
(for relatively small amounts.)