As others have mentioned, you do not need a visa. That aside, to avoid mis-counting causing you a potential overstay if you decide to stay longer, 25 Apr to 25 May is 31 days (inclusive), not 30 days. Happy trails.
You’re well on the way. Now that you have joined the group today, next you should go to this group’s landing page, and type “retirement” into the search field (magnifying glass icon at the top of the page), hit enter, then spend a few hours of your time reading the thousands of helpful previous posts and comments. You should also thoroughly review the official Thai government visa website (links available in the above mentioned posts/comments). Good luck.
I use a Skype subscription (have done for many years). For USD $20 per month, I can call almost any phone (both landlines and mobile) on the planet. As an expat who also travels often, this has been an excellent investment.
PS - Bloody hell, you jinxed me! I just received an e-mail from Microsoft, to advise me that Skype is retiring in April.
Sorry, I should have been clearer. I’m referring to people who are staying for their second 180 days, who already stayed the full 180 days previously. I will edit my post.