If your windows mobile phone has an airplane mode this is the easiest option to refresh your connection and get a new ip. based on your provider you may have a limited ip pool.
some providers will recycle the same 5 ips on your phone. so when tethering go to aspkins
IPBurger.com or ipchicken.com and check the ip address to make sure u are tracking the ip's you are using on which accounts. you do not want to link them by accident.
on iphone: u can refresh by putting it on airplane mode for 5 secs and then flipping back on. If you jail break ur phone with certain modded firmware you can tether for free on tmobile.
otherwise you can download an app from the Appstore: IPManager
this app allows you to see you internal and external ip address. you can tracking your ip's used in this app and also get a new one with the click of a button. I think the app is .99 cents
otherwise Pdanet is good options i have used this on and off for years. Free
if u wanna pay a little you can use: Myfi 2.0
Turns ur Android or Iphone in a wifi hotspot router and 5 devices can connect to it.
There is a hack to getting it free but is not easy you have to know comp pretty well.
otherwise the App is $19.99 on time fee but then u have a 5 device wifi hotspot router for free as long as you have data on her phone. This is without have to pay the 4g $30 wifi hotspot fee on sprint or verizon. or a $15 - $20 fee per month for limited data tethering on att.
Mifi 2.0 is created by Rock, a jailbreak app that allowed iphone users to install free software on their iphones and mod it. Now Rock app and Mifi is owned by the Iphone Dev team to created jail breaking and the pwnge apps.
Anyway it's pretty cool. and does what u need and more.
so there are just some details and options
have any questions about tethering drop them here.