How can I block a telephone number?

A phone with a call-blocking feature could be handy but you'd have to buy the new phone.  Also, a phone with a call-blocking feature is just that...a phone.  Although some can store 250 numbers on its block list, the displays are tiny, navigation is extensive and once you reach block-number 250, you'll have to assess which number(s) to remove.  It could be more frustrating than handy.

I bought a cheap tablet with a USB port, a USB modem and the PhoneTray call-blocking program.  All for under $100.  I have unlimited blocking, easy navigation and control of my phone.  Nomo, SCR and tiny phones are a joke.

Since you replied directly to me rather than comment directly to the author, I'll reply in kind:

1. I started off by saying that if she happens to be in the market for a new phone or phone system an option would be purchasing a phone system with call blocking.  So, yes, it is reasonable to assume that a purchase would have to be made.

2. The Panasonic call blocking database is stored in the main base and is system-wide.  Therefore, all phones on the Panasonic system would be covered by the entries made from any phone into the Call-blocking database.

3. I am a senior citizen and I have no problem with the display or font size.  Your experience may vary. 

4. I don't like to hear the phone ring, period, when the call is unwanted.  The Panasonic system takes care of this by allowing me to set it to not ring on the first ring.  Therefore, whether the call is blocked by the built-in call blocking list or Nomorobo, I never hear a single first ring.

5. The 250 number limitation, though a limiting factor, as I previously pointed out is enhanced by the ability to block number patterns (i.e. area codes, area codes+exchange), not just single numbers.  If you don't block number patterns,  the built-in database can fill up quickly and can become a management conundrum as you pointed out.

6. I have previously stayed away from after-market solutions like Phone Tray for 2 reasons; the solution placed in series with the phone line didn't pass the rings or the Caller ID info onto the connected phone wiring system that serves the entire house and with the solution placed in parallel with the phone line allowing the rings to all phones and the caller id info to be displayed on the phones but also allowed the first ring to be heard.  Now that I have discovered the feature on our Panasonic phone system to ignore the first ring, I'll probably revisit those after-market options that can be connected in parallel with the phone system.  Thanks for the reminder.