What are the best alternatives to Skype for occasional calls on iPad Air?

Continued...

The intent of 2FA (Two Factor Authentication) is to provide a high degree of assurance that secondary authentication is being performed using a service that "belongs" to (and is readily accessible by) a specific individual.

Attempting to use a communication channel to which you do not have regular/reliable access is infeasible.

Some online services support alternative authentication methods that do not rely upon receipt of codes via SMS text or email. Where supported, services may support authentication using Passkeys or one-time Verification Codes that are generated by an authentication App installed on your iPad. While both are fully supported by Apple devices running iPadOS 18.x, the latter is natively supported by your iPad5 running an earlier version of iPadOS.

Automatically fill in one-time verification codes on iPad - Apple Support

Use passkeys to sign in to websites and apps on iPad - Apple Support

In addition to native support provided by iPadOS and the iPadOS Passwords App, there are third-party authenticator Apps that provide the same capabilities - such as the Microsoft Authenticator and Google Authenticator Apps. Some third-party Password Manager Apps, should you use them, also support these features.

You should note that online Apps and services often determine the types of 2FA that they support - many now moving away from SMS codes to one-time Verification Codes and Passkeys.

In general, if you need to make or receive voice calls, having access to either a Cellular or fixed-landline telephone is unavoidable. Reliance upon online calling services, such as Skype, for occasional calling is neither practical nor feasible.

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. If you have added an eSIM or physical DataSIM with an active Cellular plan to a WiFi+Cellular model of iPad, the number associated with the DataSIM/eSIM is only used to identify your account for billing purposes. This number is not (and cannot be) used for making calls or sending messages. An iPad is not, and can never be, a standalone substitute for an iPhone.

However, when coupled 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.

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.

If applicable, the settings that you need to change/verify on your iPhone and iPad are:

On your iPhone

Settings > Mobile Data >WiFi Calling > 

• WiFi Calling on This iPhone - set to ON
• Add WiFi Calling for Other Devices - set to ON

Settings > Mobile Data > Calls on Other Devices > 

• Allow Calls on Other Devices - set to ON
• [Allow Calls On] - explicitly enable your new iPad from the list of devices.

On your iPad

Settings > FaceTime > Calls from iPhone > Calls from iPhone - set to ON

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

Continuity

Work across all of your devices seamlessly – Apple Support

SMS/MMS Messaging

Forward SMS/MMS text messages from your iPhone to your Mac or iPad - Apple Support

WiFi Calling

Make a call with Wi-Fi Calling – Apple Support

Making and receiving calls on iPad

Make and receive phone calls on iPad - Apple Support

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

In conclusion, in conjunction with an iPhone, it is theoretically possible to configure WiFi Calling service for your iPad. After WiFi Calling is enabled and configured, your iPad can 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.