My kids birthdays are coming up should I unblock him

Their Dad has been blocked for about a month now because he wouldn’t take my calls or theirs. He doesn’t send money either. I’m assuming he will try to call on their birthdays so should I unblock him or leave it as is? When they would call him it would be on Duo so he knew it was them calling and not me.

*** He use to be heavily involved when we were in a relationship but once that failed that’s when the communication tapered. If you let him tell it I’m the reason he doesn’t want to do for the kids. No custody order Or child support in place yet but I plan to file soon. I’m not the type to block my kids father from contacting them but I got fed up with him not calling anymore or answering. The last they heard from him was a Happy New Year and that was it.