Field Code for Cell Number

I would like to have a field code for guest's cell number. I ask guests to verify their cell number since I use the last 4 digits as their door lock code. It would be helpful to be able to add this field code in email templates, especially if I use a trigger with that template.
Thanks for considering this request.

Yes, guests usually do supply that number. But, I would like to be able to include their cell number automatically in an email that I send out using a trigger. Otherwise, I have to go to another tab and copy the number, paste it in my email and then send manually. Also, some people just leave the field blank, but I need that number in case I need to contact them during their stay.

Example:
Your reservation information lists your cell number as {guestcellnumber}. Please let us know if this number is not correct since we use the last 4 digits of this number as your door code during your stay.
(wording is off the top of my head... haven't composed the actual yet)

I assume it is correct..Unless they volunteer to tell me otherwise. No issues so far, but I also no longer use cell # for the key code - I use erentallock and that generates unique code for each renter - I have no control of actual digits in that code.

Thank you for the reply, Michelle. While your idea is feasible, I will just send the message manually for now and copy/paste their cell number in the door code information.