Is there an Apple alternative to Google Voice for iPad Pro?

FaceTime is Apple's alternative - although this service does not, of itself, provide a telephone number for standard landline calls.

Do you have an iPhone, or just an iPad?

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, 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.

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.

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 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.

Google Voice is one of Google's suite of Apps. Google Voice is geographically limited. Other VoIP Apps are available within the Apple App Store.

Apple invite submission of comments and feature requests via its Product Feedback portal. If you would like to see a specific feature or functionality in a future version of iPadOS, this would be the most appropriate channel through which to make a request:

Feedback - iPad - Apple

I believe I have made this “unsolicited suggestion” before, but I will gladly make it again.

Good day,

Remember you are not addressing Apple here but rather other end users. Apple won't see you suggestion among tens of thousands of new posts made here daily.

Instead, use this to place your need before an Apple employee:

Feedback - iPad - Apple

Cheers!