Cellular voice doesn't work

Question

In a complete reversal of the usual problem, I have SMS and cellular data but the phone will neither make nor receive voice calls. Skype works fine. Removing the sim and commencing an emergency call successfully connects to the network (I disconnected immediately, of course) which shows that the hardware is okay.

This phone is actually a CUBE T698 that I bought after drowning my beloved 950XL. It was running Windows Mobile 10.0.10586 and the version of Skype in that build is deprecated so I did some registry hacks to make it claim to be a 950XL and updated to 10.0.15063

I believe the problem was present prior to the update. Everything else works better especially the touch interface which is much smoother.

The sim is fine, I tried it in another phone. In the problem phone I can send and receive SMS.

So... what do I have to set to get the evil thing to send and receive cellular voice calls? The network is Telstra using an Aldimobile prepaid sim.

It works perfectly with an Optus sim.

Answer 1

It appears that this phone does not support VoLTE and does not support a voice band provided by Telstra.

These are the frequencies supported by the phone.

• 2G: GSM 850/900/1800/1900MHz
• 3G: WCDMA 2100MHz
• 4G: FDD-LTE 1800/2100MHz

These are the frequencies supported by the carrier Telstra.

• 3G: 850 (NextG) and 2100
• 4G: LTE 700, 1800, 2600

These two lists make it look like everything should work. What this data does not tell you is that Telstra support for 3G 2100MHz is limited and mostly rural.

What confused me was the fact that the phone once worked, briefly. In hindsight it must have managed to connect to a distant tower supporting 2100MHz, there's no other explanation.

So what can you do?

Optus claims to support

• 3G: 900, 2100MHz
• LTE: 700, 1800, 2300 (ACT), 2600

This is why the phone worked with a borrowed Optus sim. Amaysim uses the Optus network and has comparable pricing to Aldimobile, so I guess I will be picking up a sim for $2 from Woolworths and porting my number.

It appears that the Vodafone network would also be suitable for metropolitan use.