MOT/Phone‪+‬ 4+

MOT/Phone+ is SIP client softphone that let you use your iPhone to make an extension call.
MOT/Phone+ supports AMRNB and SILK codec for better voice quality over mobile network.
It is used in conjunction with MOT/PBX (IP-PBX) system or MOT/TEL service.

Basic Features
MOT/Phone+ has a basic features of a business telephone, including the following:
* Call via NTT-HIKARI and Japanese ITSP(050 Number)
* Integrate mobile phones into your office's phone extension network.
* Integrate iPhone Contacts into MOT/Phone+.
* Call history
* Call hold, attended transfer, park hold.
* Onetouch-key dial. (Speed dial)
* Re-dial by pressing dial button for a while.
* Ring tone settings.
* Bluetooth headset. (Only voice input/output available)
* Multi Domain. (Can be registered to two SIP server)

Application Consideration
* iPhone6s, 6s Plus, 7, 7 Plus, 8, 8Plus, X, Xs, Xs MAX, XR, 11, 11 Pro, 11 Pro Max, SE2 are supported. iOS 13 or higher supported.
* You cannot select ring tone saved in iPhone. MOT/Phone+ provides specific ring tones.
* MOT/Phone+ has own call history and which is differ from iPhone's call history.
* If you receive a mobile phone call while you're talking with your friends using MOT/Phone+ on mobile network,
the call with your friend might be disconnected due to communication restriction by mobile network operator.
au (One of Japanese mobile network operator) has this restriction but Softbank doesn't have it.
* MOT/Phone+ might not receive a phone call immediately via mobile network due to its condition or specification.
* You might meet a problem if you use MOT/Phone+ and another VoIP application such as Skype at the same time.
* Please subscribe flat-rate monthly charge service which enables economical use of packet communications.