3CX phone provides a free softphone for the Android & Iphone.  However configruing it for another Voip provider can be some what challenging.

With a lot of help & patience from Mark at Apptix Voice & a lot of trial & error we got it working with their Service.

The instructions at the link below , illustrates how we got it working with Apptixvoice , but presumably it should also work for other non 3CX Voip providers with a little tweaking

Note:  Your ISP or Cellular services provider may specifically block Voip Sip traffic.

Configuring the 3CXPhone  softphone for  VOIP services provided by Apptix Voice Mailstreet on an Android or Iphone

Thanks Mark!