Answering the telephone whilst praying
Question

                They were praying one of the prayers at home when the telephone started to ring, and it distracted them with its ringing for a long time. Is it permissible in such cases for the worshipper to take a few steps forwards or backwards and pick up the receiver and say “Allaahu akbar” or raise his voice in recitation so that the caller will know that he is praying – by analogy with (the hadeeth with speaks of) opening the door to one who knocks or raising his voice so that he can hear you?
Praise be to Allah.If 
          the worshipper is in the position that you describe and the phone starts 
          ringing, it is permissible for him to lift the receiver, even if he 
          has to move a little way forward or back, or to the right or left, on 
          the condition that he keeps facing the qiblah and he says ‘Subhaan Allaah’ 
          so that the person who is calling will know (that he is praying). It 
          was narrated in al-Saheehayn 
          that the Messenger of Allaah  (peace 
          and blessings of Allaah be upon him) used to pray whilst carrying his 
          granddaughter Umaamah. When he did rukoo’, he would put her down, and 
          when he stood up he would pick her up again. According to a report in 
          Muslim, this was when he was leading the people in prayer in the mosque. 
          (Narrated by Maalik, 1/170; al-Bukhaari, 1/487, in Sutrat 
          al-Musalli, Baab idha 
          hamala jaariyatan sagheeratan ‘ala ‘unuqihi; Muslim, 543, 
          in al-Masaajid, Baab 
          jawaaz Hamal al-Subyaan; Abu Dawood, no. 917-920; al-Nasaa’i, 
          2/45). 
 Ahmad 
          and others narrated that ‘Aa’ishah (may Allaah be pleased with her) 
          said: “The Messenger of Allaah  
          (peace and blessings of Allaah be upon him) was praying in his house 
          with the door closed.  I came (to the door) and he walked over 
          and opened the door for me, then he went back to his place.” She mentioned 
          that the door was in the direction of the Qiblah. (Narrated by Ahmad, 
          6/31; Abu Dawood, 922; al-Nasaa’i, 1/178; al-Tirmidhi, 2/497). 
 Al-Bukhaari 
          and Muslim narrated that the Messenger of Allaah  
          (peace and blessings of Allaah be upon him) said: “Whoever notices something 
          alarming whilst praying, then men should say ‘Subhaan 
          Allaah’ and women should clap their hands.” 
 And 
          Allaah is the Source of strength. May Allaah bless our Prophet Muhammad 
          and his family and companions, and grant them peace.