Orange customers will be able to roam onto T-Mobile's network, and vice versa, from 5 October.
According to Reuters, Orange and T-Mobile users will be able to switch networks whenever they have a low signal. The system will be tested until early 2011, when switching will become automatic.
The network-sharing agreement is the result of a link-up between Orange and T-Mobile earlier in the year, merging under the name 'Everything Everywhere'. The two companies now jointly represent the largest mobile group, ahead of Telefonica's O2 and Vodafone. You'll still see Orange and T-Mobile shops, though, as the brands will be kept.
The reason behind the network-sharing agreement is that Everything Everywhere wants its network quality to be as good as possible, as more and more of people use mobile Web services. Everything Everywhere has also claimed that, in the future, you'll be able to switch from mobile to fixed to Wi-Fi networks without noticing.
Orange has been busy of late. It's also decided to enhance its pay-as-you-go 'animal' tariffs by providing better rewards when you top up. Those on the 'monkey' tariff will now only have to top up £5 to earn their free-text and Internet-access reward; 'camel' customers will receive free international calling minutes when topping up £10 a month; and there's now a 12p-per-minute call rate for those on the 'raccoon' tariff, Orange's lowest flat rate. You can read more details on Orange's website.
Last week, Orange also announced plans to introduce high-definition voice calling for selected mobiles. We wondered how many people were actually going to be able to access this service, but it would be no surprise if T-Mobile customers were able to use the same technology in the future.
Late in August, we also revealed Orange's plans to develop a cheap, £200 Android tablet by the end of the year. The company's already started developing budget .
Are you on Orange or T-Mobile? Do you think the network-sharing agreement will benefit you? Let us know in the comments section below.