@ nice051

you are welcome brother. my pleasure.

+ I'm not sure about your first two question as they belong to Telecom system in Pakistan (& not to engineering theoratically) under PTA (Pakistan Telecommunication Authority) which is the regulatory authority of Telecommunication in Pakistan & prepare policies & regulations to be followed by all carriers operating in Pakistan.
Any Engg working in PTA or in private carrier (e.g. Orascom, Wateen etc) may better be able to answer your first 2 questions correctly by consulting the PTA regulation in this matter or the policy of the specified carrier.

If you are unable to find correct answer then you may contact a class mate of mine of MSTS who is working in Seimens Telecom as Network Engineer at e-mail naeemriaz888@hotmail.com by giving my reference.

regards,
sincerely,
Noman !