You are not the only user of IMO messenger and VoIP service that experienced this issue. Unfortunately, the Telecom Regulatory Authority has been insisting that all VoIP services, except for those provided by licensed operators in the UAE, are illegal. This means that from now on IMO VoIP will be blocked in the UAE, having the same status as other similar software like Viber, WhatsApp and BBM voice.
To overcome this issues, install HotspotShield VPN on your Android and you should have the possibility of using IMO again. The application is available for installation using your Play Store.