Editing UMTS (section)

== Problems and issues ==
Some countries, including the United States, have allocated spectrum differently from the [[International Telecommunication Union|ITU]] recommendations, so that the standard bands most commonly used for UMTS (UMTS-2100) have not been available.{{citation needed|date=December 2014}} In those countries, alternative bands are used, preventing the interoperability of existing UMTS-2100 equipment, and requiring the design and manufacture of different equipment for the use in these markets. As is the case with GSM900 today{{when|date=December 2014}}, standard UMTS 2100&nbsp;MHz equipment will not work in those markets. However, it appears as though UMTS is not suffering as much from handset band compatibility issues as GSM did, as many UMTS handsets are multi-band in both UMTS and GSM modes. Penta-band (850, 900, 1700, 2100, and 1900&nbsp;MHz bands), quad-band GSM (850, 900, 1800, and 1900&nbsp;MHz bands) and tri-band UMTS (850, 1900, and 2100&nbsp;MHz bands) handsets are becoming more commonplace.<ref>{{cite web|url=https://www.worldtimezone.com/gsm.html|title=GSM World Coverage Map - GSM Country List by frequency bands}}</ref>

In its early days{{when|date=December 2014}}, UMTS had problems in many countries: Overweight handsets with poor battery life were first to arrive on a market highly sensitive to weight and form factor.{{citation needed|date=December 2014}} The Motorola A830, a debut handset on Hutchison's 3 network, weighed more than 200&nbsp;grams and even featured a detachable camera to reduce handset weight. Another significant issue involved call reliability, related to problems with handover from UMTS to GSM. Customers found their connections being dropped as handovers were possible only in one direction (UMTS → GSM), with the handset only changing back to UMTS after hanging up. In most networks around the world this is no longer an issue.{{citation needed|date=December 2014}}

Compared to GSM, UMTS networks initially required a higher [[base station]] density. For fully-fledged UMTS incorporating [[video on demand]] features, one base station needed to be set up every 1–1.5&nbsp;km (0.62–0.93&nbsp;mi). This was the case when only the 2100&nbsp;MHz band was being used, however with the growing use of lower-frequency bands (such as 850 and 900&nbsp;MHz) this is no longer so. This has led to increasing rollout of the lower-band networks by operators since 2006.{{citation needed|date=December 2014}}

Even with current technologies and low-band UMTS, telephony and data over UMTS requires more power than on comparable GSM networks. [[Apple Inc.]] cited<ref>{{cite news|url=https://www.wsj.com/articles/SB118306134626851922|title=iPhone 'Surfing' On AT&T Network Isn't Fast, Jobs Concedes|first1=Nick|last1=Wingfield|first2=Amol|last2=Sharma|newspaper=Wall Street Journal|date=30 June 2007|via=www.wsj.com}}</ref> UMTS power consumption as the reason that the first generation [[iPhone]] only supported EDGE. Their release of the iPhone 3G quotes talk time on UMTS as half that available when the handset is set to use GSM. Other manufacturers indicate different battery lifetime for UMTS mode compared to GSM mode as well. As battery and network technology improve, this issue is diminishing.

=== Security issues ===
As early as 2008, it was known that carrier networks can be used to surreptitiously gather user location information.<ref name=wp814>{{cite news|author1=Craig Timberg|title=For sale: Systems that can secretly track where cellphone users go around the globe|url=https://www.washingtonpost.com/business/technology/for-sale-systems-that-can-secretly-track-where-cellphone-users-go-around-the-globe/2014/08/24/f0700e8a-f003-11e3-bf76-447a5df6411f_story.html|access-date=20 December 2014|newspaper=Washington Post|date=24 August 2014}}</ref> In August 2014, the [[Washington Post]] reported on widespread marketing of surveillance systems using [[Signalling System No. 7]] (SS7) protocols to locate callers anywhere in the world.<ref name=wp814/>

In December 2014, news broke that SS7's very own functions can be repurposed for surveillance, because of its relaxed security, in order to listen to calls in real time or to record encrypted calls and texts for later decryption, or to defraud users and cellular carriers.<ref name=wp1214>{{cite news|author1=Craig Timberg|title=German researchers discover a flaw that could let anyone listen to your cell calls.|url=https://www.washingtonpost.com/blogs/the-switch/wp/2014/12/18/german-researchers-discover-a-flaw-that-could-let-anyone-listen-to-your-cell-calls-and-read-your-texts/|access-date=20 December 2014|work=The Switch- Washington Post|date=18 December 2014}}</ref>

[[Deutsche Telekom]] and Vodafone declared the same day that they had fixed gaps in their networks, but that the problem is global and can only be fixed with a telecommunication system-wide solution.<ref name=ard>{{cite news|author1=Peter Onneken|title=Sicherheitslücken im UMTS-Netz|url=https://www.tagesschau.de/inland/umts-sicherheitsluecken-101.html|access-date=20 December 2014|work=Tagesschau|publisher=ARD-aktuell / tagesschau.de|date=18 December 2014|language=de}}</ref>