In the folowing, we will assume you use natbib with plainnat.bst, this solution will work for all standard natbib .bst files and probably the majority of .bst files - just follow the instructions below.
If you are using natbib with plainnat.bst, you will just have to modify the function FUNCTION {format.pages}.
Locate plainnat.bst on your file system, copy it to a place LaTeX can find it (a good start would be the directory your .tex file is in) and rename it (to, say, myplainnat.bst).
Open the renamed document and find FUNCTION {format.pages}, replace the function by
FUNCTION {format.pages}
{ pages empty$
{ "" }
{ pages multi.page.check
{ "pp." pages n.dashify tie.or.space.connect }%<---- changed "pages" to "pp."
{ "p." pages tie.or.space.connect }%<---- changed "page" to "p."
if$
}
if$
}
Now use \bibliographystyle{myplainnat} instead of \bibliographystyle{plainnat}.
MWE
\documentclass{article}
\usepackage{natbib}
\usepackage{url}
\begin{filecontents}{\jobname.bib}
@INPROCEEDINGS{Talaya2004,
author = {Talaya, J. and Alamís, R. and Bosch, E. and Kornus, W},
title = {Integration of a Terrestrial Laser Scanner with GPS/IMU Orientation
Sensors},
booktitle = {The International Archives of the Photogrammetry, Remote Sensing
and Spatial Information Sciences 35 (Part B7)},
year = {2004},
pages = {990-995},
owner = {Say},
timestamp = {2013.09.07}
}
\end{filecontents}
\begin{document}
\cite{Talaya2004}
\nocite{*}
\bibliographystyle{myplainnat}
\bibliography{\jobname}
\end{document}

Edit as you are using apalike.bst (you can find out what style you are using by examining \bibliographystyle{apalike}), here is the guide for apalike.
Find apalike.bst on your computer (it is probably in texmf-dist/bibtex/bst/apalike, on my machine it was in C:\Program Files (x86)\MiKTeX 2.9\bibtex\bst\apalike; if you have no idea where to find it, open a command prompt/shell and type kpsewhich apalike.bst and navigate to that file) copy it into the directory myQuestion.tex is in, rename apalike.bst to myapalike.bst.
Open myapalike.bst and search for FUNCTION {format.pages} (in my version of the file it is on line 378), you will find a block of code like this.
FUNCTION {format.pages}
{ pages empty$
{ "" }
{ pages multi.page.check
{ "pages" pages n.dashify tie.or.space.connect }
{ "page" pages tie.or.space.connect }
if$
}
if$
}
Just change the word "pages" in the fifth line to "pp." and "page" in the sixth line to "p.", so the whole function now reads:
FUNCTION {format.pages}
{ pages empty$
{ "" }
{ pages multi.page.check
{ "pp." pages n.dashify tie.or.space.connect }%<---- changed "pages" to "pp."
{ "p." pages tie.or.space.connect }%<---- changed "page" to "p."
if$
}
if$
}
Instead of \bibliographystyle{apalike} from now on use \bibliographystyle{myapalike}.
So your MWE becomes
\documentclass[12pt,twoside]{report}
\usepackage{natbib}
\begin{document}
%%%%%%%%%%%%% begin Bibliography %%%%%%%%%%%%%%%%%
\citet{Talaya2004}\
\bibliographystyle{myapalike}
\bibliography{References}
\end{document}
the bibliography looks like this

.bstfile) defines how the data should be formatted not JabRef. It only manages the data. So you shouldn't use pp in the database. – percusse Sep 08 '13 at 12:46.bstfile you are using (if you're usingbibtexand friends) or whichbiblatexstyle you are using (how about a MWE). Either way, as @percusse said, do not add something like "pp." to thepagesfield manually. – moewe Sep 08 '13 at 12:58natbib(I suppose you do),biblatex, ...? What\bibliographystyleare you using (plainnatetc.). Just show us a small yet complete document in which you cite\citet{Talaya2004}. – moewe Sep 08 '13 at 14:54