Frank Sanda, general telecom disrupter and founder and CEO of Japan Communications Inc., the provider of b-mobile products, recently announced on twitter that they are "about bring Tokyo landline numbers to mobile phones". That is, you could have a 03-xxxx-xxxx phone number attached to your smartphone. This will make your mobile number indistinguishable at a glance from a normal landline phone and will allow people to call you for a fraction of the cost they would incur if they called your mobile number.
He also said that the goal for JCI this next year is to move in the same revenue class (trillion yen) as NTT East and NTT West, and he thinks this "03 Smartphone" will do just that. And he also thinks the NTTs are going to need some help from someone, somewhere.
As far as I can see, the way this is going to happen is using VoIP ("IP softphone") with a "Class A" LTE connection. If so, not only will calling in be cheaper, so will calling out. Docomo charges ¥42 per minute to place an out-of-network call from an LTE phone. Doing the same with VoIP costs one tenth of that price, and if the connection is good, (I'll come back to that later) the voice quality is loads better due to the use of higher-quality codecs.
A bit of background:
Phone Numbers in JapanIn Japan, prefixes are typically reserved for particular types of devices. Mobile phones are allocated numbers beginning with 090, 080, and (recently), 070. Because incoming calls are charged to the caller, calling a mobile phone can be quite expensive. A commonly available option is an iP (VoIP) softphone app for your smartphone that is attached to a 050 number. However, the incoming calls to a 050 number can still incur a premium charge, above the cost of a standard local call. So, the best would be to have a normal number attached to your cellphone, for example a “03” Tokyo prefix.
Using a SIP client with a purchased 03 DID allows this right now, which is similar to what many of us do to get a phone number from “back home”. (I used to use callwithus, but now have a free DID from callcentric at which I point my Google Voice number.) While this is easy and straightforward in most countries, it is a bit more complicated here in Japan (though not impossible).
Quality of ServicePart of the reason why you can’t just get a prepackaged VoIP plan for your mobile phone with a 03 number is because there are minimum requirements before particular prefixes may be allocated. For a standard landline (固定電話) number to be allocated to a VoIP provider, the line must be CLASS A, capable of an R-factor greater than 80 for 95% of the time with less than 100 ms latency (according to wikipedia). A Class B (>70 and <150 ms) line may only be allocated to a 050 number.
A CaveatLTE is technically Class A and could qualify for a standard landline number allocation.
Realistically, I’m a bit skeptical how well this will work out. At peak times, the carriers are beyond capacity. I think the 95% of the time R factor requirement might be hard to meet. NTT East and West, as well as NTT Docomo and NTT Communications - hell, all the NTTs - are going to fight this. I’m sure all but Docomo will use the same argument that LTE doesn’t yet qualify as Class A. On top of this, you have inconsistent behavior with VoIP apps across different smartphones, as well as potential concerns with battery.