Wedding Rsvp’s who don’t respond?

I would call them rather than texting them. Like you have already experienced, it's easier to ignore texts than it is to ignore a phone call. If they don't answer, I would leave a message letting them know that if you don't hear back from them by the end of the day you'll be marking them as not attending therefore there won't be space for them if they decide to show up.

I would talk to your venue. That's not a lot of buffer time you've built in. If RSVPs are due a month ahead, which is standard, it's inevitable that there will be some that need to be chased down. Some may have never even received an invitation. If your wedding is not for 3+ weeks, it's possible the venue would be willing to give you some additional time before you need to actually guarantee, ie pay for, numbers. Many places can add a handful of additional replies last minute so that's also something else to consider.

I'd call them or a partner, contact them on social media by private message, or even attempt to reach them at work, or with family, if necessary. I would not be comfortable with the possibility of someone just showing up. Try calling at various times of the day. Unfortunately, anyone who ignores or misses your earlier message could also easily ignore or miss a message that says you'll count them as a "no."

In the end, your approach can vary depending on the relationship and the specific circumstances. There are some people I'd welcome no matter what if they were able to make it, even last minute. and others who would get the "count them as a no" message, assuming they ever hear or see it.

Definitely Call, as said by previous folks it's easy to ignore a text. (learned the hard way) Jacks gave me a fabulous line, and I used it with a little tweaking for those that DID answer the phone call: "having not heard from you, I will put you down as not attending. Unfortunately we won't be able to accommodate unannounced guests and the caterer numbers will be final" Oh, and just for a GOOD laugh to help ease your stress, a friend of mine sent me this ..........

Ha ha, I came here to give that line! OP, yes, I would make one last and final attempt to contact them. If you can't make it clear they are a "not attending" as far as you're concerned.