Yup, you guessed right. By default that's a no. However, you can do a cow-helicopter by using a 3rd party that will be a proxy between your signal account and y

Yup, you guessed right. By default that's a no. However, you can do a cow-helicopter by using a 3rd party that will be a proxy between your signal account and your whatsapp account. Hell, you can do whatever you want between any 2 services with a 3rd party. Problem is, you still need an account on both ends.