Is it possible to buy/ hire mobile phones in Hanoi? How much of the route has mobile coverage?

Yes, it’s very easy to hire or buy cell phones here in Vietnam. There are many new and used mobile phone shops. Prices are extremely cheap and buying a SIM card is very easy. If you are traveling for an extended period of time we recommend that you have a phone number for safety and for sharing your number with friends that you meet along the way. The coverage is fine in the major city centers, towns and townlettes. Once you are trekking far in the jungle or in the remote areas service begins to fade away