Assalamualaikum SS Dato’ Seri Mufti. Are we obliged to answer the adhan played on the radio and the television and do we have to supplicate after it ends?
Alhamdulillah, praise and thanks to Allah for the countless blessings He has blessed us all with. Blessings and salutations to the Prophet Muhammad PBUH, his wives, his family, companions and all those that follow his teachings to the day of judgement.
We start this with a hadith narrated by Abdullah bin ‘Amr RA where the Prophet PBUH said:
إِذَا سَمِعْتُمُ الْمُؤَذِّنَ فَقُولُوا مِثْلَ مَا يَقُولُ وَصَلُّوا عَلَىَّ فَإِنَّهُ مَنْ صَلَّى عَلَىَّ صَلاَةً صَلَّى اللَّهُ عَلَيْهِ عَشْرًا ثُمَّ سَلُوا اللَّهَ لِيَ الْوَسِيلَةَ فَإِنَّهَا مَنْزِلَةٌ فِي الْجَنَّةِ لاَ تَنْبَغِي إِلاَّ لِعَبْدٍ مِنْ عِبَادِ اللَّهِ أَرْجُو أَنْ أَكُونَ أَنَا هُوَ فَمَنْ سَأَلَ لِيَ الْوَسِيلَةَ حَلَّتْ لَهُ الشَّفَاعَةُ
“When you hear the Mu'adhdhin, repeat what he says, then invoke a blessing on me, for everyone who invokes a blessing on me will receive ten blessings from Allah; then beg from Allah al-Wasila for me, which is a rank in Paradise fitting for only one of Allah's servants, and I hope that I may be that one. If anyone who asks that I be given the Wasila, he will be assured of my intercession.”
Sahih Muslim 384, Sunan Abi Dawud 523 and Sunan al-Nasai’e (679)
While, a hadith narrated by Jabir bin Abdullah RA, the Prophet PBUH said:
مَنْ قَالَ حِينَ يَسْمَعُ النِّدَاءَ اللَّهُمَّ رَبَّ هَذِهِ الدَّعْوَةِ التَّامَّةِ وَالصَّلاَةِ الْقَائِمَةِ آتِ مُحَمَّدًا الْوَسِيلَةَ وَالْفَضِيلَةَ وَابْعَثْهُ مَقَامًا مَحْمُودًا الَّذِي وَعَدْتَهُ، حَلَّتْ لَهُ شَفَاعَتِي يَوْمَ الْقِيَامَةِ
"Whoever after listening to the Adhan says, 'Allahumma Rabba hadhihi-dda` watit-tammah, was-salatil qa'imah, ati Muhammadan al-wasilata wal-fadilah, wa b`ath-hu maqaman mahmudan-il-ladhi wa`adtahu' [O Allah! Lord of this perfect call (perfect by not ascribing partners to You) and of the regular prayer which is going to be established, give Muhammad the right of intercession and illustriousness, and resurrect him to the best and the highest place in Paradise that You promised him (of)], then my intercession for him will be allowed on the Day of Resurrection".
Sahih al-Bukhari (614), Sunan Abi Dawud (529) and Sunan Ibn Majah (722)
Syeikh Abdul Karim Kudhair stated: “Adhan which is played by any device and is live from Masjidil Haram through radio or any main masjid of a particular town, it is considered as the actual adhan and we are commanded to answer it. Live version of the adhan through radio is the same as of with the usage of loudspeaker.
However, if the adhan is a recorded version (from cassette or CD) and not live, then we consider the muezzin as not being there. Hence, the adhan is not obligatory to be answered and does not carry the ruling of actual adhan”. 
However, we are of the opinion of as long as we hear the adhan from the radio either if it is recorded or live, then the ruling of Sunnah to answer the adhan is prioritized because it is part of the eminence of the religion. Besides, the range of distribution of adhan through radio and TV is much wider than the adhan from some mosques. Both adhan; in mosque or in radio or TV are important to remind the ummah on the calling for prayer.
May Allah choose our ancestors and us to be among His servants who are consistent in mainatining prayers. Ameen.
We close this with a du’a:
رَبِّ اجْعَلْنِي مُقِيمَ الصَّلَاةِ وَمِن ذُرِّيَّتِي ۚ رَبَّنَا وَتَقَبَّلْ دُعَاءِ ﴿٤٠﴾ رَبَّنَا اغْفِرْ لِي وَلِوَالِدَيَّ وَلِلْمُؤْمِنِينَ يَوْمَ يَقُومُ الْحِسَابُ ﴿٤١﴾
My Lord, make me an establisher of prayer, and [many] from my descendants. Our Lord, and accept my supplication (40) Our Lord, forgive me and my parents and the believers the Day the account is established." (41)
Surah Ibrahim (40-41)
 Refer: http://almoslim.net/node/133719