I've played quite a bit of email and phone tag with different departments representing the City of Jacksonville and haven't been able to get a solid straight answer.

Would also love to speak over phone/zoom if anyone is willing. 

(What kind of cold calling software can I get to acquire phone numbers?)

(There are other ways to obtain/develop that evidence - such as using certified mail or my “practical advice” below.)In your case, because your friend found the letter inside the mailbox of the last known address, you now have specific evidence of having mailed the letter “…by first class mail, to the tenant's last known place of residence” - “Unless other arrangements (had been) made in writing by the tenant…”Again, in my (non-lawyer) opinion, you’ve complied with the letter of the law as to your concern - “Unless other arrangements (had been) made in writing by the tenant…”[Practical advice: Where I self-manage, in my “Notices” section of the lease, besides my physical address, phone numbers, etc for notices to me, I provide two email addresses for myself, and state in that part that email is my preferred method of communication.

This structure is not cheap to setup initially, and the annual admin costs are substantial, however gives peace of mind that it offers the ultimate liability protection and most efficient tax structure. 

Is it possible to hide phone number from the listing?

I called up Harris County, gave the address and they let me know over the phone.  

if you could find a way to do it virtually or by phone calls, you could definitely get some business because i’m interested. 

It doesnt work with my phone so when I am on the phone I just use quote.

Might be easier on a brief phone call.