IF an EMP occurs, Your Cell phones would be rendered useless anyhow, only reliable form of communications after a post EMP scenario would be HF with an NVIS setup for long distance communications. You can use anything between 3-30Mhz for long to short distance communications.

I would not consider an EMP burst as a high threat scenario. Odds are greater that a natural disaster would disrupt your lines of communications or a few well placed conventional explosives at key sites that provide communications support/services. And they can render Cell Phones, Standard Repeater or trunked based VHF/UHF communications useless (ie police,firefighters etc..)