Why shouldn't I use my company mobile exclusively?

Is it a smartphone and do they have it locked down at all?  I have my work phone that I use as a phone but I can't install any apps on it.

For me, my bank issued phone is, for regulatory reasons, prohibited from texting, taking pictures, and accessing certain websites (Gmail, Facebook, Twitter, youtube, etc...).

If this isn't an issue for you, then I see no reason why you wouldn't save the $$$ and use the free phone.

iPhone 5S, free to do as I wish with apps and everything else.  My company is pretty dang lax on that stuff.  

In that case I suppose the only reason I can think of is that the phone is still technically the property of your company. They may take that further and say that the phone and the information stored in the phone is their property.

My last job was with the County government, we had a big problem with employees using their County email for personal use despite many warnings against it. So we finally started monitoring, a few people got fired over it and it caused a big uproar. At the end of the day, the email address and the computer and everything on it belonged to the County so there was no reasonable expectation of privacy.

You may want to see if your company has a policy on this. Unless of course you don't mind them reading your personal texts, emails and listening to your voicemails. 

And that's the usual argument against and the reason I ask.  Do I have reason to believe they would even bother?  Not at all, however, I do fully understand that if they ever wanted to they could.  I guess my question to that is how easy is that accomplished for them?    I'm a bit tech stupid when it comes to that.  At the end of the day I work for a smallish family owned and ran company, not some huge conglomerate or city/state/fed entity.  It all seems a bit conspiracy theorist to me but I'm open to other thoughts.  

Could be as easy as when you come into work on a Monday morning they ask you to hand over their phone and that they will give it back at the end of the day.

Technically it is their phone so you don't have much of an ability to refuse to hand it over.

Also they can go online and see who you are calling, who is calling you. Probably can't read the actual text messages without a lot of hassle but can see what numbers they are going to and coming from. 

It's really up to you, if you are comfortable with your boss taking your phone for 4 hours and going through it then probably not a big deal. If you would rather they did not see certain things you keep on your phone then it would be best to have a personal phone. Like I said, if Mr. Boss demands you hand over his phone I don't see a way you can refuse. 

Eh......if you come to work one day and they say, "hand over your phone", and there is something on there that you can be fired over....just refuse and walk out.  It's not like they're going to tackle you for it, and you were going to be fired anyway.  

And make sure on your way out of the parking lot you accidently drop it and run over it.

I see no reason to not use it for personal use.

I understand all that COULD happen although I think my risk for it is pretty low.  I guess I just need to decide if the minor risk outweighs the inconvenience of lugging two phones, so far it does.  

Yeah, very situation dependent. If you feel comfortable with the minor risk and don't generally do anything on your phone that could get you in trouble it is probably worth it to not carry two phones around. 

I've ran into this a few times, and there are pro's and cons to both.  The pro's are fairly obvious because it's more convenient and saves you money.

With it being a company owned phone it's a company owned phone and number.  So if/when you leave the company you will likely have to get a new number (and go buy a phone).

As was mentioned being that it's a company phone they have the right to view and/or restrict what is on your phone.  So, if you like to go to bikini sites to help you go to sleep at night they can see that if they want to.
I just did a presentation yesterday at a large school district and we sell a Mobile Device Management (MDM) solution for student and school devices on their network and you'd be amazed at what we can track.  The MDM client installs an agent on your phone that shows where you're at all the time in the building and even sends a heat map to show where employees/students congregate during the day.  Any managed device can be pulled up on a map to pinpoint its location 24/7 via GPS.  It's basically a full time GPS tracking device if they put the software in place.

I'm not going all conspiracy theory on this stuff because there are valid reasons for schools/businesses to do these things.  I just think it's important to be informed on what they can do and read their policy thoroughly.  
So, depending on your comfort level with their phone policy and what software they utilize internally to track their mobile devices I would use that to weigh the pros and cons of using it.

Unless I had a really tight budget, and this would make a real difference to me that way, I'd keep my own phone.  I'd rather not have to change my contact information in the many places I have already stored my personal phone number.  I would also not like to have to run to the store the day I lost the work phone (whether for good or bad reasons).    It's very nice to be able to keep the same number, transfer my contacts and things if I get a new phone, etc. 

On a side note as a business owner I had to decide on company phones or personal ones.  Our business requires our employees to have a cellphone and use it as part of their jobs, so I offered to buy them a cellphone with a plan.  However, most didn't want that so I ended up just giving them the choice of $100/mo. cellphone allowance or a company cellphone for free.  I don't have a single person (including myself) that has a company owned phone.  lol

You may ask them if they would give you the option to just take a cellphone allowance and get rid of your company phone and just use your personal phone for both.

This is actually how I've always been with previous companies, I supply my own phone and plan and they reimburse.  Unfortunately, this company doesn't work that way.

As for GPS, even though I doubt they'd go that route I would have to have the phone with me almost 24/7 regardless.  So personal phone in addition or not, I'm tethered to the work phone.  

Greatly appreciate everyone's input on this.  

Based on how you describe your company I highly doubt they have any tracking software in place.  It does cost quite a bit of money and companies that purchase it are usually ones interested in keeping assets from walking off.  Schools are huge customers because they have thousands of iPads roaming the halls and it gets quite expensive when they grow legs.  

We just had a guy leave the business and hand over his work phone. He now has no phone and anyone that tries to contact him is unable to do so. That'll work itself out in a few weeks, I'm sure. However, for me, work is work, home is home. The 2 rarely overlap, even though I am a 24/7 employee. I'm not into conspiricies and don't believe Big Brother is watching me, but I am more comfortable keeping my "stuff" private. So, I carry 2 phones. given their size, it really isn't a problem for me.

One other point from the business side of things. We were doing the reimbursement thing here right up until a sales guy left with his personal phone and ended up taking a couple of opportunities with him, since the customers called his phone number. There are pros and cons to everything, as someone else mentioned.

I've used my work phone (iPhone 5 right now) as my personal phone for 5 or 6 years. I have yet to find a down side. I don't do anything questionable on the phone so am not worried about Big Brother. 

I do realize that when I leave I'll have to get a new phone and number. No biggie. That  risk is vastly out-weighed by being handed a free iPhone, unlimited everything, and no bill - for years on end.

I'll be handed a business phone soon, too.  I'll ONLY use it for work - meaning I'll answer it when someone calls me for work-related needs (web site/server is down, etc.) or if I have to call out to a colleague/boss (I don't support the Exchange mail server or if I can't reach the Exchange mail server administrator).