URL Networks Softphone application can be installed on your Windows or Mac PC, Android or iOS Smart Phone to allow you to make and recieve calls from your Office Cloud Hosted PBX Phone System.
FAXing over VoIP networks doesn't work. You can sometimes arrange things so a fairly high percentage of FAXes get through OK. You can occassionally create setups that work 100% of the time. These are rare and unrepeatable setups. You need to use a proper FAX over IP protocol, such as T.38, to achieve consistent reliable FAXing across IP networks.
If using the Outlook Windows client and cannot send email as a shared mailbox. Switch off Cached Exchange mode. This will force Outlook to use the GAL permissions for send as instead of (likely) out of date cached local permissions.