The phone is mentioned whenever the idea of connection is shown in the text. This applies to when the man receives phone calls, to when Changez wants to connect and call his family after the 9/11 attacks.
But more importantly, whenever the phone appears during the interaction of Changez and the man, Changez describes the phone as an “unusual phone” and seems like Changez suspects something of the phone.
When Changez first sees the man’s phone, he is highly observant of the type of phone he has, stating that it is “capable of communicating via satellite when no ground coverage is available.” Changez knowing this piece of information also makes him more curious as to who the man is what he is doing on this specialised phone. Changez says he will do his “utmost to avoid eavesdropping on your conversation” which sounds highly suspicious, almost as though he is signaling to the man that he is going to try his best to eavesdrop and find out more about the man. The “utmost” being italicized further suggests the suspicion behind Changez’s speech and makes the readers question his true intentions about listening in on the man’s phone call. However, when the man decides to text instead of pick up the phone, Changez seems upset, turning his attention to the group of girls to avoid having his disappointment revealed.
The second time Changez mentions the man’s phone, he continues to try to find out more about the man and who he is contacting, asking him questions about who is on the other side of the phone, before quickly giving up as to not look too desperate for answers “No, you need not answer”. Chanez’s observance is noted here again, from how he notices that the man checks his phone precisely on the hour.
The phone is mentioned one last time near the end of the book. At this point, it seems as though Changez has given up trying to figure out more about the identity of the man on the other end of the phone. We can see this from how he cooperates with the man, telling him to text his friend that “we are not far from your hotel—another fifteen minutes at the most,”.
From this, we can tell that the phone not only symbolises connection between people, but also secrecy for when the man is o the phone. As readers, just like Changez, we are unsure of who is on the other side of the line, nor do we know what the man is texting his collegue.