contact numbers saved gets automatically deleted without knowledge

Hey there atul223,

Thanks for reaching out to Apple Support Communities. I understand the numbers you have associated with your contacts are being removed unexpectedly. I’ll be happy to help with this.

First, make sure your iPhone is up to date:

Update your iPhone, iPad, or iPod touch

Once you’ve done that, create a new contact and see if the issue returns. Also, open the Contacts app and tap on a contact card that you experienced this issue with. See if the number shows in the contact card.

You may also want to check which accounts are syncing contacts in Settings > Passwords & Accounts as well as which account is the Default Account in Settings > Contacts. 

If the default account is not iCloud, switch to iCloud and try creating another contact card. See if the issue occurs with this contact.

You can read more about this here:

Use other contact accounts on iPhone

If you still have issues, let me know what accounts you’re syncing with your iPhone and if this issue seems to affect contacts in a certain account.

Take care.

Are you sharing an Apple ID with anyone?