What is 'Ultra Set', made-in-China telecom handset being used by Pakistan army to help terrorists in India

Encounters with terrorists in Jammu and Kashmir have led to the seizure of highly encrypted Chinese telecom gear termed 'Ultra Set', an equipment reportedly used by the Pakistani army that has ended up in the hands of terror groups in Jammu and Kashmir. Officials told news agency PTI that these specialised handsets, exclusively customised by Chinese companies for the Pakistan army, were seized after a gunfight in the intervening night of July 17-18 last year in the Sindarah in Jammu region's Poonch district and in April 26 this year after an encounter in north Kashmir's Baramulla district.
What exactly is 'Ultra-Set' and how is it different
“Ultra-Set” refers to highly encrypted Chinese telecom gear that has come into focus due to its use by terror groups in Jammu and Kashmir. These specialised handsets are said to be exclusively customised by Chinese companies for the Pakistan army.
The 'Ultra-Set' handsets combine cell-phone capabilities with specialised radio equipment, operating on radio waves for message transmission and reception. Unlike traditional mobile technologies (GSM or CDMA), they rely on a unique communication mechanism.
Each 'Ultra Set' is said to be linked to a control station located across the border, the officials said and added that the two 'Ultra Sets' cannot reach out to each other. They said Chinese satellites are used to carry these messages that are compressed to bytes from the handset to the master server in Pakistan for its onward transmission.
China reportedly has been actively enhancing the defence capabilities of the Pakistani army along the Line of Control (LoC) for quite some time now. This support includes the construction of steelhead bunkers, provisioning of unmanned aerial and combat aerial vehicles, installation of encrypted communication towers and laying of underground fibre cables.
In addition, Chinese radar systems such as those of the "JY" and "HGR" series have been deployed to improve target detection capabilities, while advanced weaponry like the SH-15 truck-mounted howitzer has also been observed at various locations along the LoC.