Try this website or do a search in GOOGLE - Telecommunications salaries
http://www.payscale.com/salary-survey/vid-3507/fid-6886 If you are able to talk to your manager or boss then I do not see the harm in asking the question. You do not have to give them an ultimatum - give me a pay rise or else.
I am the Communications Specialist for a large Hospital campus which has two main PABXs and two remote PABXs (one at another Hospital)which I maintain and programme. I also mange any Cablers which come on-site and was the Project manager for a 2000 extension move from one building to another. Plus voicemail, MOH, GSM devices attached to PABX, IVR, RVA, consoles, etc.
I have been doing this job for the last three years.
For the past year I have been negotiating a pay rise, which I will sign my new contract tomorrow.
The position was valued between $60K and $80K Australian, I was able to negotiate $70K, mainly because of the amount of programming I am able to do on the PABXs. It has been a long fight, but well worth it.
But having said that it all depends on if you are happy in your job and are happy getting paid what you are, is whether or not you think the fight is worth it.
I have also increased my knowledge and training over the last couple of years. And I still have a lot to learn.
I know jobs are tough to come by in the Telecommunications Indutry, I recently advertised for and hired a junior. The job cleary stated Junior Position at $35K but the amount of responses I had from people who were obviously overqualified was overwhelming.
I do not think I am irreplaceable as the responses to my job advertisement cleary showed. But myknowledge of all sytems that the hospital deals with goes a long way, as does a good repore with my peers and management. If you do a good job and solve problems quickly and effectively then yes your conpany is not likely to look for someone new.
Good luck whatever you decide to do.