I appreciate the responses very much. I have some thoughts on changes for the future of this possibly with the mobile twinning.
However, I failed to give enough details. The calls via key system numbers, actually go to a key system where the department is locally off site. OPX lines. Then if no one answers there, either daytime possibly if all the techs are traveling or night. On "no answer" the speed call goes to the answering svc, the dept manager has given the answering service the On Call numbers.
So it would be the dept manager who would want to remotely change the On Call numbers, not me.
But, I believe you are saying, If I set up some phantom DDI as hot desk user, they can call into those extensions and change the mobile number ?
THanks again.