store contacts on modern SIM?

[SaltdeanSteve]

My father-in-law has an old Doro Easy phone 612. He's 87 and both visually and hearing impaired. He is familiar with this old 2G phone and I got a new O2 Classic PAYG SIM for it October 2020. Recently the display broke, so unable to access contacts etc to transfer to anything else. Not visible in files when connected by USB to PC. So bought "as new" replacement on eBay and spent many hours manually entering contacts, ICE data and emergency cascade details (oh, for a keyboard!). To prevent this happening again I set the "new" phone to store contacts (only about 20) to SIM when I set it up a few days ago. Now most contacts have disappeared and I can't see them if i switch to phone storage either. It has saved 3 contacts once and all the O2 service numbers (which he'll never use) twice. I know SIMs used to store only one number per contact for up to 250 entries, but are modern SIMs less capable in this regard? Or is the phone itself faulty?

[Cleoriff]

A modern sim can store over 200 contacts. The only problem is, if the phone or sim is damaged you will lose all your contacts. My android phone has all contacts saved to the device. If I lost the phone, I could still recover the contacts. I recently changed phones and all contacts were transferred automatically.

Some info here which may help..

https://justaskthales.com/en/saving-contacts-sim-phone-email-explained/ 

See here for creating a phonebook entry on a Doro 612 easy phone

https://www.doro.com/globalassets/inriver/resources/manual_doro_phoneeasy_612_en_v30r15051.pdf