While many markets can support mobile competition, regulation may be necessary to support the competitive process. Apart from stopping anti-competitive conduct, there are some regulatory initiatives which could support a more competitive mobiles market.
With digitisation regulators will come under pressure to protect mobile operators from ‘over-the-top’ applications that reduce the voice and text revenues that are significant for mobiles. However, mobile operators should be encouraged to adapt their business models to accommodate competition (see Box 2.10). These applications will make regulatory initiatives like mandated call selection redundant .
A regulatory instrument that has been used extensively to promote competition in mobiles is mobile number portability (MNP). European Law treats number portability as a human right under the EU Universal Service Directive that has applied since July 2003. But in other countries, especially smaller developing countries, the benefits and costs of implementing number portability should be considered carefully. The technical options employed in large markets for MNP may be too costly for small countries and they will be overtaken by technological changes which will change how we think about numbering and customer switching.
Box 6.10: Bahrain and MNP
The Telecommunications Regulatory Authority (TRA) got interested in mobile number portability in 2003 and decided to proceed in 2008 and implemented MNP in July 2011 (and fixed number portability in October 2011).
Mobile porting takes place within1-3 days for mobile with subscribers given a new SIM card. The maximum porting charges will be BHD 4 (about US$10).
The TRA, which is bearing the costs of the centralised system, is hoping that up to 20 per cent of mobile customers will exercise the MNP option.
The SIM card that links each customer to a mobile operator can also present a barrier to switching . On some networks, the mobile phone is ‘locked’ so that specific carrier's SIM cards will work. This is more common in markets where mobile phones are heavily subsidised by the carriers, and the business model depends on the customer staying with the service provider for a minimum term (typically 12 or 24 months). Common examples are the GSM networks in the United States, Canada, Australia, the UK and Poland .
In countries where the phones are not subsidised (e.g. Italy, India and Belgium), all phones are unlocked. Where the phone is not locked to its SIM card, the users can easily switch networks by simply replacing the SIM card of one network with that of another while using only one phone. Customers may swap SIM cards to change an off-net call into an on-net call; or to access better international call rates on another operator.
 South Africa was proposing to become the first country to impose carrier pre-selection on all mobile networks but the postponed implementation date of 30 November 2011 seems to have been missed.
 The SIM holds personal identity information, cell phone number, phone book, text messages and other data. It can be thought of as a mini hard disk that automatically activates the phone into which it is inserted.
 However, many businesses offer the ability to remove the SIM lock from a phone, effectively making it possible to then use the phone on any network by inserting a different SIM card. Mostly, GSM and 3G mobile handsets can easily be unlocked and used on any suitable network with any SIM card.