I assume you are referring to the Confirm/Reject/Notify plugin (you did not say) so I created a forum(s) for it that did not exist. Thanks for pointing that out.

Regarding your question, the CRN plugin has a filter you can use to add your branding like so (as you know, this will only work if using one-way communications):

add_filter('wppizza_crn_sms_branding', 'mysmsbranding');
function mysmsbranding($sms_sender_id){
	/* 
		overwrite sender id as required (here set to MyShop123 )
		a-zA-Z0-9 (and spaces) only, 11 characters max
	*/
	$sms_sender_id = 'MyShop123';
return $sms_sender_id;
}

(not tested as such, but should work I would think)

@Silo I would recommend the Goodcom printers they are relatively easy to use after setup. You can use Wifi or sms and you can use reject/accept + give a time for delivery to orders.

i guess people get the printers from here (at least I know some do )
https://www.aliexpress.com/wholesale?SearchText=goodcom

some of the printers (but I do not know if all) DO support an accept/reject function and some will support WiFi as well as SMS (and some only WiFi, you’d have to look at a particular printers specification)

however, the wppizza plugin itself does not “listen/talkto” – so to speak – to the printer rejecting/accepting/receiving an order.
That said , I am in the middle of finalizing an addon (tested with the GT6000 as well as the newer GT90, so one would think it would work with other reasonably recent goodcom printers too) that will do that.

Might be a week or two away though until this plugin will be released, as I need to tidy up a few things still

hope that helps

>The restaurant wishes to enable guest checkouts to increase conversion rates whilst maintaining the ability to Remarket email and SMS promotions in the future.

and this would be completely illegal. never mind GDPR (which may or may not apply to that restaurant)
it’s simply called SPAM

You can do this using the Zapier email parser combined with Twilio. Once the order is placed you can fire an SMS to your client and have them confirm the order by replying to the SMS message. Make sure it is forwarded to your phone so you can receive the answer and then proceed to get the order completed.

this has been asked and answered many times for many scenarios
please search the forum
https://support.wp-pizza.com/search/sms/

(see also https://support.wp-pizza.com/topic/after-every-order/)

you will have to use (and implement) an email 2 SMS gateway.
which one is suitable depends on your location as there are carrier charges involved.
if you search this forum for SMS , you will also find additional info

Sorry, but you are asking questions i cannot answer.

a) i know nothing about your printer, so anything related to that printer you will have to ask the manufacturer/merchant you bought it from

b) re: which SMS / Mail2Fax plugin…
there are no wppizza sms/mail2fax plugins.
there are however many (e)mail2fax services.
which one – if any – would be the right one in your circumstances i have no idea and cannot advise you (i do not even know or indeed understand why you would want any if you have a gprs printer)

all i can say is that there are codesnippets here you *might* be able to use with your setup/printer/smsgateway etc

how exactly you would have to code or setup things in your scenario I have no knowledge about.
I know nothing about your sms gateway, printer or any other API of anything else you are referring to above.

my *guess* would be the following:
you do not need to download any plugin, but will need someone to – programmatically – connect your printer using the API that your printer provides using the codesnippets.