Using for iPad as a phone

Once enabled and fully configured, WiFi Calling is very reliable; I use it all the time.

It is, however, critical that it is fully configured and enabled (and tested) prior to losing access to the iPhone - as it is only from the iPhone (that provides Cellular Services to the iPad) that WiFi Calling can (and must) be explicitly enabled for other devices:

Here is a [hopefully] complete list of settings that you’ll need to configure for both iPhone and iPad...

On iPhone:

• Settings > Mobile Data > WiFi Calling > WiFi Calling on This iPhone - set to ON
• Settings > Mobile Data > WiFi Calling > WiFi Calling For Other Devices - set to ON - and explicitly enable your iPad and other devices from the device list
• Settings > Messages > Text Message Forwarding - explicitly enable your iPad from the device list
• Settings > Messages > MMS Messaging - set to ON if you use MMS in addition to SMS messaging

On your iPad:

• Settings > [Your Name / AppleID] > Messages - set to ON
• Settings > Messages > Text Message Forwarding - explicitly enable for your iPad and/or other devices
• Settings > FaceTime > Calls from iPhone > Calls from iPhone - set to ON and explicitly enable WiFi Calling (service activation may take several minutes/hours. Once active, the service wording in iPad Settings will change in Settings to indicate that calls can be made over WiFi).

When you’re satisfied that your settings are correct, shut-down your iPhone - and test/verify both WiFi Calling and SMS Messaging features from the iPad.

I hope this is helpful in preparing the necessary services - and fully solves the requirement.

The answer to your question is not a simple binary yes or no response. Read on...

An iPad, whether a Cellular model or not, is not capable of directly accessing Cellular Voice or Messaging features. An iPad with Cellular connectivity alone can only access IP-data services. An iPad is not, and can never be, a standalone substitute for an iPhone.

However, If paired with an iPhone, the capabilities of iPad significantly broaden to include access to Cellular Voice and Messaging services of the associated iPhone - relayed to the iPad over WiFi using Apple’s continuity features. For the most part, an iPad using Continuity is able to access Cellular calling features, of the iPhone, when both the iPad an iPhone are in close physical proximity and are connected to the same WiFi network - but this is not the end of the story.

Now, if your both your Cellular Carrier and your calling plan support WiFi Calling, your iPad can make and receive calls independently of the iPhone - even when the iPhone is switched off, elsewhere, or using a different WiFi network. Not all carriers support full WiFi calling - and many Carrier representatives don’t technically understand or acknowledge its existence.

[NB: Many contributors here don’t understand the full implementation of WiFi Calling either - perhaps because this feature is often only available from some full-service cellular carriers; cut-price MVNO cellular operators may not offer the service at all].

More information about Continuity and the relevant Cellular services can be found here:

Continuity

https://support.apple.com/en-gb/HT204681

SMS/MMS Messaging

https://support.apple.com/en-us/HT208386

WiFi Calling

https://support.apple.com/en-gb/HT203032

When correctly configured, the iPad FaceTime App provides access to Cellular Voice Calling features - whilst Messages supports SMS/MMS messaging services.

So, in conclusion, if your own Cellular Carrier and tariff support WiFi Calling, it is theoretically possible to configure WiFi Calling service for your iPad - before switching off and removing the SIM card from an iPhone (e.g., before sending for repair). After WiFi Calling is enabled and configured, your iPad can continue to make and receive cellular calls whilst connected to a WiFi network (caveat: any associated firewall must not block WiFi Calling or VoIP services) - even in absence of the iPhone.

I hope this information and clarification is helpful in resolving your immediate needs.

iPads need an iPhone to make/receive phone calls, as per this support guide:--> Make and receive calls on your Mac, iPad, or iPod touch - Apple Support

Regards

Giulio