Level 1: Cadet

Caller ID Issue when roaming in Japan

Hi All,

I have been made aware of an issue that we have recently starting having whilst our staff are roaming in Japan.

Firstly, the user is on an iPhone6s with iOS9.1 and hasn’t previously noted having seen this issue.

The situation is that when a call is received whist in Japan on the SoftBank network the caller id numbers are prefixed with a random country code. For example, one call received from an Australian mobile calling within Australia to the service roaming in Japan was prefixed with +82 and shown as being from South Korea.
Switching providers on the handset (Settings -> Carrier) to DOCOMO was able to resolve calls from mobile phones, but calls from Australian landlines were then showing as blocked callers.

The situation is causing frustrating for staff as although numbers shown by the caller id can be deciphered they are not recognised by the phone as per the saved contacts so caller name information is not displayed.

Any assistance would be greatly appreciated.





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Level 23: Superhero

Re: Caller ID Issue when roaming in Japan


I'm quite sure this is not a phone issue, but an idiosyncracy of the Japanese networks and their routing and re-routing systems.

Even though I have worked in a local mobile network exchange 16 years ago, you would be absolutey surprised at the routing arrangements networks have to cope with traffic,  network use,  congestion and backhaul.

Some networks like Telstra use their own cables for routing, whereas Optus and VHA use microwave, and not always a direct route due to traffic.

It is a miniature maze compared to the Asian networks and their various private roaming arrangements.


Don't worry, it's certainly not your phone. 

If I have helped you, a "Like" would be appreciated.

If my advice is a solution, please acknowledge it.

I'm not a Telstra employee.
50 + years exp. in radio comms., eg mobile phones since 1963, two-way radios, base stations, antennas & pagers. Expert in current Telstra Go repeaters & smart antennas.
"Being 76 years of age, entitles one to be an expert at everything!!"
Telstra (Retired)
Telstra (Retired)

Re: Caller ID Issue when roaming in Japan

Hi Curious_Mind,


You'll need to contact the provider you're connected to in Japan about this particular issue.


-Matt W

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