Assistant Commissioner of Police K. Srinivas Rao on Wednesday said they were analysing the call details.
Talking to reporters, he dismissed as rumours reports doing the rounds on the social media about the last call made by Kodela, as Rao was popularly known.
The conversation Kodela had during his last phone calls could throw light on the reasons for him taking the extreme step.
Kodela hanged himself at his residence in the posh Banjara Hills neighbourhood on Monday.
The ACP said so far they have questioned 12 people as part of the investigations into the suicide case. The statements of Kodela's wife and daughter were also recorded.
Police officials said the statement of Kodela's son Sivarama Krishna will be recorded soon.
Krishna, who was abroad, returned home on Tuesday and is currently in Guntur district of Andhra Pradesh to perform his father's last rites.
The ACP said the police were yet to receive the final autopsy report.
Kodela's daughter P. Vijayalakshmi told police in her complaint that she found him hanging from the ceiling around 11.10 a.m. when she went to his room on the first floor to inform him that she was going to a hospital with her mother.
Vijayalakshmi told police that with the help of the driver and gunman, she lowered his body to the floor and then shifted him to Basvatarakam Indo-American Cancer Hospital where doctors failed in their efforts to revive him.
Police have sealed the room where the senior Telugu Desam Party (TDP) leader hanged himself. The investigators, who gathered clues from the scene, were also examining the medicines the deceased leader was using.
Vijayalakshmi, in her police complaint, alleged that the YSR Congress Party (YSRCP) government in Andhra Pradesh was harassing her father politically to take revenge. She said false cases were filed against him and other family members. She alleged that the government was continuously harassing him mentally due to which he got depressed and took the extreme step.
Kodela, who had also served as minister in undivided Andhra Pradesh, is suspected to have used a cable to hang himself after he reportedly failed in using a cloth for the purpose.
As Kodela was staying at his residence in Hyderabad for 20 days, police sources also believe that he had planned the suicide.
Terming Kodela's suicide as a murder by the YSRCP government, TDP President N. Chandrababu Naidu has demanded a probe by the Central Bureau of Investigation (CBI). The former Chief Minister alleged that the harassment by the government and the insults he was subjected to pushed him to end his life.
Kodela and his son were last month booked by Andhra Pradesh police for allegedly diverting Assembly furniture to unauthorized premises. Some furniture was recovered from a motorbike showroom belonging to Sivarama Krishna in Guntur.
The YSRCP, however, has rubbished the TDP allegations. Its leaders claimed that Naidu was responsible for Kodela's death as he was sidelining him. They also alleged that differences in the family led to the suicide.
Meanwhile, the funeral procession of Kodela began in his home town of Narsraopet in Guntur district amid tight security.
( With inputs from IANS )