I must be able to reach you. Therefore, you must have a telephone number that I can reach you at. Even if I receive your voicemail, you should be able to return my call promptly. I am not going to call you for frivolous things as that would be inappropriate. However, if I need to reach you for whatever the reason, I should be able to.
If you are in need of a smartphone, you can acquire a Technology Allowance which you can get a smartphone. While you may not be able to get a flagship with that amount, you should be able to get a good phone that will accept a SIP? client. The SIP client requirements is only required for the maintenance, and realty agent. In Office receptionists will have a desk phone that they will use for their job, but will still need a personal telephone number.