I would be surprised if temporal estimation was not affected by presence/absence of mobile phone. I think the effect would be mediated by a number of factors such as phone engagement etc. Also, those who are stimulated by other sources of reward will probably be less affected by phone absence compared to others.
The question concerns the issue of dependence on smartphones, which is becoming a serious problem for some young people. Smartphones are now an example of imperfect adjustment or non-adaptation of the technical gadget to the developmental and psychophysical needs of young people. In addition, in a situation of dependence on the use of smartphones, not only an individual problem of an addict appears, but it is also a serious social problem. The negative individual and social costs of this problem are borne by citizens and society, not the companies that these smartphones produce.
Yes I agree with you dear Slavoljub Hilčenko that today be long without the phone ... but most of our work and communicate with others is done by phone