Pulsgram has four ways in. Whichever you pick, it is the same account and it follows you to any phone.
Email and password
You type your email address, get a confirmation code from no-reply@pulsgram.com and choose a password. The code works for 10 minutes and accepts five tries. You can ask for a new one after 60 seconds, at most five times an hour for the same address.
If the address already has an account, you get an email telling you how to sign in instead of a code. That is on purpose: nobody can use the sign up screen to find out who has an account.
Apple, Google or Facebook
Tap the button and confirm with the provider. Facebook also has to give us your email address; without it we cannot create the account. If you use Apple's "Hide My Email", our emails reach your Apple relay address.
Link several methods to one account
In Settings → Sign-in methods you add or remove Apple, Google or Facebook. An account created with a provider can also get a password, through Forgot password?.
If Apple, Google or Facebook gives us an address that already belongs to another Pulsgram account, you see "You already have an account with this email". We never merge accounts on our own, because that is how someone could take over yours. Sign in with the method you already have, then link the provider in settings.
Your phone number
It is an optional profile field, used only so friends can find you from their contacts. Your account does not depend on it. Change it or remove it any time. More in How friends find you.