imessage always waiting for activation

See if the tips in the following articles help resolve the issue.

If you get an error when trying to activate iMessage or FaceTime

iMessage Waiting for Activation? How to Fix iMessage Not Working Errors on Your iPhone - iPhoneLife

iMessage is carrier specific service. You need to have data plan loaded on to your plan. Contact them and ask of internet plan and then activate.

"Waiting for activation........" :- waiting for carrier's server to respond, Apple has no role to play in this waiting.

Set up cellular service on iPhone

The cellular connection on your iPhone requires a SIM from a carrier; contact your carrier to set up a cellular plan.

iPhone X and earlier models support one cellular plan using a nano-SIM.

iPhone XS, iPhone XS Max, and iPhone XR support Dual SIM using a nano-SIM and an eSIM (not available in all regions; iOS 12.1 or later).

iMessage and FaceTime uses internet data. If your network is bad the then you may have difficulty is sending iMessage and call on Face Time

It is always better to use Wifi during FaceTime

Once the iMessage is activated then FaceTime will automatically get activated

Set up iMessage and SMS/MMS on iPhone - Apple Support

https://support.apple.com/en-in/guide/iphone/set-up-imessage-and-smsmms.../ios