There are several ways in which your your young person can use their phone to access support.
They can call university support services (usually during office hours) or local and national charities (often 24/7 or out-of-hours). Their university website will have a list of local and national charities including their contact details.
There are also charities, such as Shout, that offer a textline. If they are in distress they can text and someone will reply 24/7. Shout can be reached by texting 85258.
Finally, there are numerous apps available to download that help them look after their health and wellbeing. For example, SAM is an app which helps them manage social anxiety.