It may be cheaper to get a new handset in a package deal. These deals are offered by retailers, phone shops or directly from network service providers. If you buy a handset and connection with a retailer you may be entering into two different contracts. One contract with the network service provider for connection to the mobile phone network, and another with the retailer for the handset.
It's important to know who you are contracted to, particularly if warranty repairs are needed or you have problems with the service.